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Biomedical subjects

A Harrison

Publications and source records attributed to A Harrison.

At least 19 recordsLinked to original sources
PubMed1992

A survey of complete denture prosthetics for the elderly, the handicapped and difficult patients.

A survey was carried out to establish information on the facilities and management of the elderly and the handicapped and to evaluate the treatment of the difficult edentulous patient in general dental practice. A postal questionnaire was sent to a total of 1090 dentists in three regions of England and Wales. There was a 50.4% response. Ninety-nine per cent of practitioners were able to treat the ambulant elderly, whereas only 72% offered treatment if the patient was wheelchair dependent. Ninety-six per cent of all respondents undertook domiciliary visits. All practitioners provided prosthetic treatment (complete and partial dentures) for the elderly, whereas fewer felt able to treat the physically and the mentally handicapped. There was less conservative and periodontal treatment provided than prosthetic treatment. A similar pattern was obtained in all three regions. Forty-seven per cent preferred to treat difficult complete denture patients privately, 44% under the NHS and 6% not at all. There were regional variations in the referral patterns of these difficult denture cases. The majority of respondents considered that there should be more opportunities for postgraduate education in prosthetic dentistry.

Aged↗
PubMed1992

Dimensional accuracy and stability of acrylic resin denture bases.

Proponents of injection molding systems have claimed a number of benefits over conventional press-pack dough molding systems. The aim of this study was to evaluate a recently developed injection (dry heat) procedure of processing compared with press-pack dough molding utilizing three curing cycles. The dimensional accuracy and stability of acrylic resin bases produced by the two molding procedures were compared. Dimensional changes were assessed over a period of 4 months using an optical comparator. The results demonstrate that baseplates produced by the injection molding procedure exhibit less shrinkage than those produced by the conventional press-pack procedures.

Acrylic Resins↗
PubMed1992

Effect of the curing cycle on residual monomer levels of acrylic resin denture base polymers.

It has been shown previously that high levels of residual monomer have a deleterious effect on the properties of denture base polymers. Levels of residual monomer were determined on a homopolymer and a copolymer using gas-liquid chromatography. A wide range of recommended and 'short cut' curing cycles were then investigated which produced values ranging from 0.56 to 18.46%. From the ranges examined an optimum cycle of 7 h at 70 degrees C and 1 h at 100 degrees C was established which was used to polymerize 23 currently available synthetic denture base polymers. Only small differences were found between the materials tested with a range from 0.54 to 1.08% of residual monomer.

Acrylic Resins↗
PubMed1992

Determination of doughing and manipulation times of acrylic resin denture base material and a proposal for a specification for a packing plasticity test.

The doughing and manipulation times of a range of acrylic resin denture base polymers are presented in this study. The methods evaluated were: (i) probing following American Society for testing materials specification, F451-76; (ii) hole penetration following British Standard, 2487: 1989 and International Standard Organisation, 1567: 1988; (iii) probing using a penetrometer employing a 20 g load and 1 mm diameter needle; (iv) oscillating rheometer apparatus used at a fixed frequency of 1 Hz by sweeping through a programmed linear increase in strain. The results indicate that each of the methods is capable of evaluating the doughing and manipulation times of the unprocessed polymers. It is concluded that the Bohlin VOR Oscillating Rheometer is excellent for investigating the flow properties of denture base polymers but it cannot be recommended for a standards specification test because of the high cost. The penetrometer method has been shown to be superior to the current standards specification test and would be ideal for a packing plasticity standards test.

Denture Bases↗
PubMed1992

67Ga-9N3 uptake by xenografts of human melanotic melanoma in mice.

Tumour uptake of the inert, neutral complex 67Ga-9N3 and the tumour:blood concentration ratio (1,4,7,triazacyclononane-1,4,7, triacetic acid) were measured in mice bearing xenografts of the human melanotic melanoma HX118. Between 1 and 4 h after the injection the tumour:blood ratio increased from 3.5 to 21 and the concentration of 67Ga-9N3 in the tumour decreased from 0.43 to 0.13% g-1. During the first 24 h the concentration of 67Ga-9N3 in the tumour exceeded that in all other tissues except the liver and kidneys. The tumour:blood ratio and tissue distribution of 67Ga-9N3 at 4 h were compared with those of four other complexes. The results indicated that of the five complexes 67Ga-9N3 would be the most suitable for tumour imaging at early times after administration. Imaging would not be restricted to gamma emitting 67Ga as there is also the possibility of using the 9N3 ligand to bind 111In for single photon emission computed tomography (SPECT), 68Ga for positron emission tomography (PET) or even stable Ga for direct in vivo nuclear magnetic resonance (NMR) detection.

Animals↗
PubMed1991

Measurement methods used for the determination of dimensional accuracy and stability of denture base materials.

The literature relating to methods of measurement of dimensional accuracy and stability of denture base materials is reviewed. The papers are presented chronologically together with information on the measurement technique used and the reported level of accuracy. Most authors utilized optical measuring apparatus, with the use of calipers being the second most popular method.

Dental Materials↗
PubMed1991

The in vivo release of 90Y from cyclic and acyclic ligand-antibody conjugates.

Yttrium binding ligands DOTA, caDTPA and CT-DTPA were each conjugated to monoclonal antibody B72.3, labelled with 90Y and injected into mice in order to assess the in vivo inertness of the antibody-linked 90Y-ligand complexes. Levels of 90Y in femur shafts of the DOTA-B72.3 mice were low, being approximately 7 and 44%, respectively, of levels in the femur shafts of the caDTPA-B72.3 and CT-DTPA-B72.3 treated mice. This finding demonstrates the greater inertness and by implication the greater suitability for immunotherapy of the DOTA-90Y complex.

Animals↗
PubMed1991

Childbirth in Kuwait: the experiences of three groups of Arab mothers.

The aims of the present study were to characterize the childbirth experiences of three groups of Arab mothers delivering in Kuwait and to evaluate the use of visual analog scales (VAS) for assessing their pain (N = 301). Kuwaiti, Palestinian, and Bedouin women who were expected to have an uncomplicated vaginal delivery were studied. 73% of the women described their maximum labor pain as "unbearably painful," and more than one-half reported that they were "very frightened" or "terrified." The deliveries of Bedouin mothers were remarkable for the absence of pain behaviors; yet their VAS reports indicated that they experienced no less pain. Painful menstruation and fear of childbirth emerged as risk factors for a painful labor. Among the issues discussed are the validity of the VAS data, the difficulties of managing Bedouin mothers' pain, and the importance of excluding physical factors before cultural differences in pain perception are assumed.

Delivery, Obstetric↗
PubMed1991

Arabic children's pain descriptions.

A convenience sample of 60 children, aged five to 12 years, reporting to Kuwait government hospital emergency departments was studied. All were native Arabic speakers. Our aim was to compare the diagnostic usefulness of the pain information provided by children and by accompanying adults when interviewed under standard emergency department conditions. Children were asked to describe their current pain and how it had changed and to signify pain intensity using a 10-point visual analog scale (VAS). Comparable data were then collected from the accompanying adult. Senior clinicians rated these verbal and VAS descriptions for their usefulness in arriving at a diagnosis. Most children provided useful pain information. Mothers received consistently higher scores for their VAS descriptions than their children did; otherwise, the pain data provided by adults were not judged to be significantly more useful. When clinicians and teachers were asked to differentiate which data they thought had been provided by a child and which by the accompanying adult, nearly half of their decisions were wrong.

Adult↗
PubMed1991

Assessing patients' pain: identifying reasons for error.

Accurate pain assessment is vital for good medical care, and yet the literature indicates that nurses often provide inaccurate and biased estimates of their patients' pain. The following paper reviews the methods used to assess nurses' accuracy, and reasons offered for the errors observed. Practical options for improving pain assessment and pain management are discussed.

Attitude of Health Personnel↗
PubMed1991

The effect of thermocycling on the hardness of soft lining materials.

This investigation studied the effect of thermocycling on the hardness of six commercially available soft lining materials. The apparatus used to measure hardness measured the difference between depth of penetration of an indentor into a specimen under a primary contacting load and a secondary penetrating load. Control specimens were stored in water at 20 +/- 2 degrees C and trial specimens were thermocycled between 18 +/- 1 degree C and 53 +/- 1 degree C for periods up to 28 days. It was found that thermocycling had a deleterious effect on the softness of all six materials. Further, it was shown that chairside provisional soft lining materials demonstrate a rapid deterioration at temperatures greater than 50 degrees C.

Cold Temperature↗
PubMed1990

Complete denture construction in general dental practice: an update of the 1970 survey.

A survey was carried out on materials and techniques used for complete denture construction in general dental practice, by means of a postal questionnaire sent to a random sample of 1000 dentists whose names were taken from the BDA membership. There was a 71.5% response. The results obtained are compared with a similar survey undertaken in 1970. The majority of practitioners still provided dentures totally or mainly within the NHS. Whilst the demand for complete dentures was reported as having remained stable, there has been considerable reduction in the numbers of dental technicians employed by general dental practitioners. Alginate remains the impression material of choice and the majority of impressions were sent to a commercial laboratory for pouring. Although still the most popular, the use of the plane-line hinge articulator has reduced and there has also been a continued reduction in the use of porcelain teeth. The importance of a cross-infection policy is highlighted. There were conflicting opinions expressed on the role of implants in general dental practice. Many respondents took the opportunity to comment on the status of dental prosthetics under the NHS and most criticised the fee structure.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Distribution of microtubules containing post-translationally modified alpha-tubulin during Drosophila embryogenesis.

The distribution of microtubules (MTs) enriched in detyrosinated alpha-tubulin (Glu-tubulin) was studied in Drosophila embryos by immunofluorescence microscopy by using a monoclonal antibody (ID5) which was raised against a 14-residue synthetic peptide spanning the carboxyterminal sequence of Glu-tubulin (Wehland and Weber: J. Cell Sci. 88:185-203, 1987). While all MT arrays contained tyrosinated alpha-tubulin (Tyr-tubulin), MTs rich in Glu-tubulin were not found during early stages of development even by using an image intensification camera. Elevated levels of microtubular Glu-tubulin were first detected after CNS condensation in neurone processes. In addition, sperm tails, which remained remarkably stable inside the embryo until late stages of development, were decorated by ID5. This was in marked contrast to the distribution of microtubule arrays containing acetylated alpha-tubulin, which could already be detected during the cellular blastoderm stage. Additional experiments with taxol suggested that the absence of MTs rich in Glu-tubulin during early stages of development was not due to the rapid turnover rate of MTs, which would be too fast for alpha-tubulin to be detyrosinated. The possible significance of the differential detyrosination and acetylation of microtubules during development is discussed.

Acetylation↗
PubMed1990

Rheology of acrylic denture-base polymers.

The aim of this study was to investigate the changing rheological behavior of a denture-base polymer from mixing to setting. In addition, monomer evaporation and exothermic behavior of the mix were evaluated. The results show that the material behaves as a pseudoplastic fluid. It is shown that the viscosity increases at different rates with respect to lapsed time, and increases with higher temperature. Also, it is shown that polymerization and monomer evaporation both play a part in dough formation.

Acrylic Resins↗
PubMed1990

The effect of the alpha-particle emitter astatine-211 in the mouse at the minimum toxic dose.

The radioactive halogen astatine-211 was injected into mice in an amount producing minimal toxicity. Histopathological examination of tissues at intervals between 3 d and 16 weeks showed the following changes: 1. Radiation-induced necrosis and progressive fibrosis of the thyroid gland. The gland was reduced to 25% of its original mass with only a few relatively normal follicles persisting. 2. A small, temporary, reduction in peripheral blood lymphocytes, platelets and red cells and a significant persistant increase in polymorphs. 3. Severe reduction in reproductive cells in the testis with some signs of recovery at 16 weeks.

Animals↗