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Biomedical subjects

D Read

Publications and source records attributed to D Read.

At least 19 recordsLinked to original sources
PubMed2005

Naturally occurring radioactive material (NORM) from a former phosphoric acid processing plant.

In recent years there has been an increasing awareness of the radiological impact of non-nuclear industries that extract and/or process ores and minerals containing naturally occurring radioactive material (NORM). These industrial activities may result in significant radioactive contamination of (by-) products, wastes and plant installations. In this study, scale samples were collected from a decommissioned phosphoric acid processing plant. To determine the nature and concentration of NORM retained in pipe-work and associated process plant, four main areas of the site were investigated: (1) the 'Green Acid Plant', where crude acid was concentrated; (2) the green acid storage tanks; (3) the Purified White Acid (PWA) plant, where inorganic impurities were removed; and (4) the solid waste, disposed of on-site as landfill. The scale samples predominantly comprise the following: fluorides (e.g. ralstonite); calcium sulphate (e.g. gypsum); and an assemblage of mixed fluorides and phosphates (e.g. iron fluoride hydrate, calcium phosphate), respectively. The radioactive inventory is dominated by 238U and its decay chain products, and significant fractionation along the series occurs. Compared to the feedstock ore, elevated concentrations (< or =8.8 Bq/g) of 238U were found to be retained in installations where the process stream was rich in fluorides and phosphates. In addition, enriched levels (< or =11 Bq/g) of 226Ra were found in association with precipitates of calcium sulphate. Water extraction tests indicate that many of the scales and waste contain significantly soluble materials and readily release radioactivity into solution.

Calcium Sulfate↗
PubMed2002

Percutaneous dilational tracheostomy: a safer technique of airway management using a microlaryngeal tube.

Management of the airway in an intubated patient during formation of a tracheostomy can be hazardous. The usual method involves withdrawal of the tracheal tube, which has been providing a secure airway, prior to inserting the tracheostomy tube. A method of airway management, using a microlaryngeal tube, has been devised with the aim of maintaining full tracheal intubation and ventilation until the correct position of the tracheostomy tube can be verified. An audit of 250 successive cases of percutaneous tracheostomy demonstrated this method to be safe and effective.

Adolescent↗
PubMed2001

Which Is Better: Simultaneous or Sequential Choice?

The term "diversification bias" refers to the tendency for people to take more variety when choosing several items simultaneously than when choosing them sequentially. In this article, we investigate whether this really is a bias by measuring evaluations of sets chosen simultaneously or sequentially. In Experiment 1 participants made two choices between audio tracks for consecutive consumption. Participants liked low-variety sets most and were more likely to choose high-variety sets in simultaneous choice. In Experiment 2 participants chose between three gambles which varied in the probability of winning and their expected value. Again, simultaneous choices seemed worse than sequential ones: The simultaneous-choice groups took far more low expected value gambles than did sequential-choice subjects and rated their enjoyment as lower. We conclude that simultaneous choice often leads to outcomes that are worse than sequential choice and discuss the circumstances when this is likely to be true.

Journal Article↗
PubMed2001

An age-embedding effect: time sensitivity and time insensitivity when pricing health benefits.

Benefits are often extended over time. One determinant of this benefit duration is how long a person will live to enjoy them. In four studies, we investigated whether people are sensitive to age when pricing benefits that will last for the remainder of one's life. In Study 1 drivers gave their willingness-to-pay (WTP) to cure a medical condition which would stop them from driving. Results showed an age-embedding effect: WTP was unrelated to the estimated number of driving years left. Study 2 tested whether age-embedding arose because people have a lot of information about themselves which dilutes the impact of age on their valuations. In Studies 3 and 4 we investigated whether people believed that age was an important consideration, or if they failed to properly incorporate it into their judgment. Results indicate that little weight is given to age when making individual pricing decisions, although people did not believe it was normatively irrelevant.

Adult↗
PubMed2000

Functional studies of the BTB domain in the Drosophila GAGA and Mod(mdg4) proteins.

The BTB/POZ (BTB) domain is an approximately 120 residue sequence that is conserved at the N-terminus of many proteins in both vertebrates and invertebrates. We found that the protein encoded by a lethal allele of the Drosophila modifier of mdg4 [mod(mdg4)] gene has two mutated residues in its BTB domain. The identities of the residues at the positions of these mutations are highly conserved in the BTB domain family of proteins, and when the corresponding mutations were engineered into the BTB domain-containing GAGA protein, the activity of GAGA as a transcription activator in a transient transfection assay was severely reduced. The functional equivalence of the BTB domains was established by showing that the BTB domain of the mod(mdg4) protein can effectively substitute for that of GAGA.

Active Transport, Cell Nucleus↗
PubMed2000

Bilateral adrenal non-Hodgkin's lymphoma with adrenal insufficiency.

A 74 year old women presented with lethargy and weight loss and was found to have profound adrenal insufficiency and bilateral adrenal mass lesions. Histological examination revealed non-Hodgkin's lymphoma. There was no evidence of lymphoma outside the adrenal glands. Isolated bilateral adrenal masses may rarely be due to primary adrenal non-Hodgkin's lymphoma, which is often associated with adrenal insufficiency.

Adrenal Gland Neoplasms↗
PubMed1998

Predicting Hunger: The Effects of Appetite and Delay on Choice.

Preferences often fluctuate as a result of transient changes in hunger and other visceral states. When current decisions have delayed consequences, the preferences that should be relevant are those that will prevail when the consequences occur. However, consistent with the notion of an intrapersonal empathy gap (Loewenstein, 1996) we find that an individual's current state of appetite has a significant effect on choices that apply to the future. Participants in our study made advance choices between healthy and unhealthy snacks (i.e., fruit and junk food) that they would receive in 1 week when they were either hungry (late in the afternoon) or satisfied (immediately after lunch). In 1 week, at the appointed time, they made an immediate choice, an opportunity to change their advance choice. Our main predictions were strongly confirmed. First, advance choices were influenced by current hunger as well as future hunger: hungry participants chose more unhealthy snacks than did satisfied ones. Second, participants were dynamically inconsistent: they chose far more unhealthy snacks for immediate choice than for advance choice. An additional hypothesis related to gender differences was also confirmed. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

The efficacy of different methods for informing the public about the range dependency of magnetic fields from high voltage power lines.

The AC electric and magnetic fields associated with high voltage power lines have become a concern as a possible health risk. In most cases the strength of these fields decreases as the inverse square of the distance from the line. In earlier work, we found that laypeople do not understand how rapidly field strength decreases with distance. Most believe that any high voltage power line they can see is exposing them to strong fields. This paper confirms the earlier finding and explores a number of strategies which might be used in risk communications to correct this misperception. We found it relatively easy to provide subjects with a better understanding of the range-dependency of magnetic field strength. Moreover, the quality of this acquisition was apparently independent of the manner in which they were instructed. Such successful instruction is markedly different from the well-established difficulty of teaching people about many qualitative domains, such as physics or ideas in probability. Clearly, while some erroneous beliefs are highly resistant to change, others can be altered quite readily. We suspect that an important distinction between knowledge about the range-dependency of power-frequency magnetic fields and less tractable topics involves the presence or absence of prior folk-theories or "mental models" of the domain.

Adolescent↗
PubMed1998

Cancer incidence, morbidity and geothermal air pollution in Rotorua, New Zealand.

BACKGROUND: The New Zealand city of Rotorua sits on a geothermal field. However, little is known about the possible health impacts of the geothermal emissions. This was an ecological study that examined cancer incidence and morbidity data for Rotorua. METHODS: Cancer registry and hospital discharge (morbidity) data were obtained for the decade 1981-1990. Standardized incidence ratios (SIR) were calculated comparing Rotorua residents with those living in the rest of New Zealand. Diagnostic categories examined were based on known target organ systems of hydrogen sulphide toxicity. RESULTS: Of the cancer sites, there was an elevated rate for nasal cancers. However, this was based on only four cases. The SIR for cancers of the trachea, bronchus and lung in Maori women was 1.48 (95% CI: 1.03-2.06). This was not explained by higher smoking rates. In the hospital discharge data, a number of diseases showed elevated SIR, notably diseases of the nervous system and the eye. To some extent, these effects were characteristic of effects induced by hydrogen sulphide and also mercury compounds. However, there were few data with which to assess whether significant mercury exposures had occurred, and other explanations were possible. CONCLUSIONS: There are inadequate exposure data for Rotorua to permit conclusions on likely causal associations. However, some of the elevated disease rates were at least consistent with what one might expect to find if sufficient exposures to hydrogen sulphide and/or mercury were occurring.

Air Pollutants↗
PubMed1998

Capturing tumour stage in a cancer information database.

OBJECTIVE: 1. To present the steps taken and lessons learned from one cancer centre's efforts to capture tumour stage information in a cancer database. 2. To determine the accuracy of the stage data through a chart audit. 3. To describe the potential uses of stage information in a cancer centre. DESIGN AND SETTING: This is a retrospective review of an initiative to capture tumour stage information at a regional cancer centre in Ontario. DATA SOURCES: The minutes of the centre's Health Records and Medical Advisory Committees related to staging were reviewed. Data on stage by tumour type was extracted from the centre's Oncology Patient Information System (OPIS). Three hundred and ninety charts were analysed to assess the accuracy of stage information and identify staging errors. Health Information Services workload statistics were reviewed to determine the types and frequency of projects undertaken using stage-related data. RESULTS: In January 1994, the Ottawa Regional Cancer Centre introduced policies and procedures to capture stage-related information. Standardized staging forms and a physician reminder system encouraged the centre's physicians to record tumour stage within 3 months of new patient registration. Of all qualifying cases in 1994, 92% were staged. A medical audit in 1998 of 390 charts from the 3 previous years of staging data revealed that 71.5% of the charts reviewed had been staged completely. Of the incompletely staged cases, 19% to 57% had TNM recorded, but the stage grouping was not recorded, or the "stage" was the extent of disease at the time of disease progression rather than at initial diagnosis (35% to 71%). Physician-related staging errors occurred in 2% to 5% of cases; data-entry errors occurred in 3% to 6% of cases. CONCLUSIONS: Stage information has enabled the centre to better describe its patient clientele for accreditation purposes and to assist researchers in estimating the number of patients potentially available for prospective and retrospective studies. It is being used to guide targeted educational initiatives to selected populations in the region's catchment area and assists administrators in estimating resource needs. Resistance to the capture of stage information can be overcome with persistence, the development of procedures that facilitate physician compliance, including a reminder system, the development of institutional policies and procedures and by feedback on the uses and availability of stage information.

Accreditation↗
PubMed1997

Air pollution and mortality in the Rotorua geothermal area.

The effects on human health of geothermal emissions in the Rotorua area have been little studied. We calculated standardised mortality ratios (SMRs), comparing residents domiciled in the Rotorua territorial local authority area with those living in the rest of New Zealand, using mortality data for the decade 1981-1990. The SMRs were adjusted for age, calendar year, sex, and ethnicity. Diagnostic categories examined were based on known target-organ systems of hydrogen sulphide toxicity. Mortality causes examined were diseases of the nervous system and sense organs, diseases of the circulatory system, diseases of the respiratory system, and birth defects. Of these, notably elevated SMRs were found only for diseases of the respiratory system, particularly in Maori women (SMR = 1.61, 95 per cent confidence interval 1.19 to 2.12). A major concern was the possibility of confounding by ethnicity. This is because ethnicity in census data is based on self-identification, whereas ethnicity on death certificates is often based on funeral directors' impressions. This leads to serious underreporting of Maori mortality statistics. For the purposes of this study, this situation was further complicated by indications that ethnicity recording for Maori may be more accurate in the Rotorua area than in the rest of New Zealand. Our analysis suggested that, in general, SMRs based on ethnicity are likely to be spuriously high. Although this study found no clear indications of excess mortality in the Rotorua area likely to have been associated with geothermal emissions, there were limitations in the data that could have prevented the recognition of causal associations.

Air Pollutants↗
PubMed1995

Lead in children from older housing areas in the Wellington region.

AIMS: To examine blood lead levels in children, aged 12 to 23 months, living in old housing areas of Wellington and Lower Hutt, and to investigate risk factors for high lead levels. METHOD: Children were selected from Plunket Society rolls. Venous blood samples were collected, and care givers were interviewed with a questionnaire. Soil samples were taken from around the children's homes. Both soil and blood samples were analysed for lead content. RESULTS: Blood samples and completed questionnaires were obtained for 143 children. The geometric mean blood lead level for all the children was 0.25 mumol/L (5.1 micrograms/dL) (95% confidence interval [95% CI]: 0.22-0.28 mumol/L). Three children had blood lead levels that exceeded the level for notification in New Zealand 1.45 mumol/L and a further 13 had blood lead levels exceeding 0.48 mumol/L. Children with elevated lead levels were likely to live in a house greater than 50 years old where paint removal had taken place in the last 2 years (risk ratio [RR] = 14.4, 95% CI: 2-107). Eating dirt, particularly for children who usually played outside within 2 metres of the house, was also a risk factor for elevated blood lead levels. Soil lead levels generally increased with the age of the house and were weakly correlated with blood lead levels (r = 0.32). CONCLUSION: Paint removal in old houses is a major risk factor for elevated blood lead levels. However, the number of study children living in houses less than 50 years old was limited. Because of this and possible participant selection bias, the results of this study require confirmation in a separate population-based study. Information about the specific paint removal procedures that cause high lead levels is also needed.

Cross-Sectional Studies↗
PubMed1995

Plasmodium falciparum: parasites defective in early stages of gametocytogenesis.

Some molecular characteristics of Plasmodium falciparum lines which do not produce gametocytes are described. Parasites carrying a subtelomerically deleted chromosome 9 cannot form even the earliest forms of gametocytes, detectable with antibodies against the gametocyte-specific antigen Pfg27. In a parasite culture of clone HB3, in which both intact and deleted forms of chromosome 9 are present, full-length chromosome 9 molecules are retained mainly in gametocytes. These data suggest that the subtelomeric portion of chromosome 9 is required at an early stage of gametocytogenesis. Parasite subclones derived from gametocyte producing clone 3D7, which completely lost ability to produce gametocytes, are also described. Unlike the previous gametocyteless lines, these parasites stably maintain a full-length chromosome 9 and the ability to cytoadhere to C32 melanoma cells after prolonged asexual propagation. Their defect in sexual development is therefore genetically and functionally distinct from that of parasites carrying a deleted chromosome 9. Gametocyteless subclones derived from 3D7 do not produce any Pfg27 mRNA, while this gene is anomalously expressed in asexual stage parasites of two lines of a different genetic background, 1776sel8 and C10, one able and the other unable to produce gametocytes.

Animals↗
PubMed1995

Botulinum versus tetanus neurotoxins: why is botulinum neurotoxin but not tetanus neurotoxin a food poison?

Botulinum and tetanus neurotoxins, produced by Clostridium botulinum and Clostridium tetani, respectively, are the most poisonous poisons known to mankind. Although botulinum and tetanus neurotoxins share several characteristics, such as similar mol. wts, similar macrostructure, virtually identical mode of action, and a strong amino acid sequence homology, the two neurotoxins differ in one very significant way; only botulinum neurotoxin is a food poison. Factors responsible for the food poisoning potential of botulinum neurotoxins seem to be a group of complexing proteins that are also produced by C. botulinum, and are known to associate with the neurotoxin. Translation products of nucleotide sequences upstream to the neurotoxin genes of serotypes A, B, C, D, E and F botulinum neurotoxin reveal the location of genes for one of the complexing proteins that could be transcribed as polycistronic mRNA to include neurotoxin sequences. No such protein seems to be present in C. tetani, suggesting that the lack of complexing proteins might be responsible for tetanus not being a food poison.

Amino Acid Sequence↗