Biomedical subjects

David Fowler

Publications and source records attributed to David Fowler.

At least 37 records · Page 2Linked to original sources

PubMed2005

Practical considerations for addressing uncertainties in monitoring bulk deposition.

The assessment of the deposition of both wet (rain and cloud) and dry sedimenting particles is a prerequisite for estimating element fluxes in ecosystem research. Many nations and institutions operate deposition networks using different types of sampler. However, these samplers have rarely been characterized with respect to their sink properties. Major errors in assessing bulk deposition can result from poor sampling properties and defective sampling strategies. Relevant properties are: sampler geometry and material, in particular the shape of the rim; sink properties for gases and aerosols; and microbial transformations of the collected samples. An adequate number of replicates allows the identification of samples which are contaminated, in particular by bird droppings. The paper discusses physical and chemical properties of the samplers themselves. The dependence of measurement accuracy on the number of replicates and the sampling area exposed is discussed. Recommendations are given for sampling strategies, and for making corrections and substitution of missing data.

Air Pollution↗

PubMed2005

Deposition monitoring networks: what monitoring is required to give reasonable estimates of ammonia/ammonium?

Deposition is one of the main loss terms for ammonia and ammonium from the atmosphere. It is also the input for ecosystems that can lead to drastic changes and effects. Deposition networks are needed to evaluate the need and the effect of policies to reduce nitrogen emissions, but also for studying deposition parameters and for developing deposition models. As with ambient concentrations of ammonia, deposition, especially dry deposition, varies strongly in space and in time. Furthermore, the bi-directional surface-atmosphere exchange of ammonia makes the combination of ambient concentration measurements with inferential models inadequate. Developing deposition monitoring networks with reasonable accuracy and representativeness is therefore not straightforward. In Europe several projects have addressed deposition monitoring. From these results it is concluded that a monitoring strategy should consist of a network with a limited amount of super sites combined with a larger number of sites where low cost methods are applied, together with models for generalisation.

Air Pollutants↗

PubMed2005

Tissue distribution of loperamide and N-desmethylloperamide following a fatal overdose.

We report a case involving a fatal intoxication with loperamide (Imodium). Loperamide is a synthetic opioid of the phenyl piperidine class used as an over-the-counter antidiarrheal. It exerts its effects through interaction with micro-opiate receptors in the intestine to reduce peristalsis. Loperamide lacks the typical euphoric opiate effects when administered at recommended doses. Both loperamide and its major metabolite, N-desmethylloperamide, were isolated by liquid-liquid extraction into n-butyl chloride from alkalinized samples. Extracts were analyzed by liquid chromatography-electrospray-mass spectrometry in selected-ion-monitoring mode. Rapid separation of the drug, metabolite, and internal standard (diphenoxylate) was achieved using a high-resolution C18 column with 1.8-microm particle diameter. The mobile phase consisted of 0.1% formic acid in deionized water (60%) and acetonitrile (40%) at a flow rate of 0.5 mL/min. Heart blood concentrations for loperamide and its metabolite were 1.2 mg/L and 3.3 mg/L, respectively. In contrast, reported peak plasma concentrations of loperamide after administration of recommended daily doses of 16 mg did not exceed 0.012 mg/L in controlled trials. Because the heart blood ethanol concentration was 0.08 g/dL, the medical examiner ruled that the cause of death was loperamide and ethanol intoxication, and the manner of death as undetermined.

Adult↗

PubMed2005

The psychology of persecutory ideation II: a virtual reality experimental study.

A cognitive model of persecutory delusions is used to predict the occurrence of nonclinical paranoid thoughts in a virtual reality environment. Scorers across the range of paranoia entered a virtual reality scene populated by five computer characters programmed to behave neutrally (N = 30). Many appraisals of the computer characters were positive or neutral. However, there were also persecutory thoughts about the characters. Providing evidence of the validity of the experimental method, persecutory ideation was predicted by higher trait paranoia and a greater sense of presence in the environment. The psychological variables from the cognitive model that predicted persecutory ideation were anxiety, timidity, and hallucinatory predisposition. Further, hallucinatory predisposition distinguished the prediction of paranoid thoughts from social anxiety in virtual reality. It is concluded that nonclinical paranoid thoughts are most closely associated with emotional disturbances and anomalous experiences. Extreme reasoning bias may particularly contribute to the development of clinical phenomena.

Adult↗

PubMed2005

The psychology of persecutory ideation I: a questionnaire survey.

Paranoia is a complex phenomenon that is likely to arise from a number of factors. In a recent cognitive model of persecutory delusions, three key factors are highlighted: anomalous experiences, emotion, and reasoning. In the first of two linked studies, we report a questionnaire survey of nonclinical paranoia designed to assess the theoretical model. A nonclinical population (N = 327) completed measures of paranoia, anomalous experiences (hallucinatory predisposition, perceptual anomalies), emotion (depression, anxiety, self-focus, stress, interpersonal sensitivity), and reasoning (need for closure). Paranoia was best explained by separation anxiety, depression, fragile inner self, hallucinatory experiences, discomfort with ambiguity, stress, self-focus, perceptual anomalies, and anxiety. The findings are consistent with the central predictions within the model of paranoia.

Adult↗

PubMed2005

Trauma and hallucinatory experience in psychosis.

Recent research indicates that there may be phenomenological, symptom, and diagnostic associations between trauma and hallucinations. However, the nature of the relationship is poorly understood from a psychological perspective. We report a theoretically informed phenomenological study. From descriptions of reported traumas and hallucinations, we assessed the rates of four types of hypothesized association between traumas and hallucinations (direct, indirect, stress, and none) in 75 participants with nonaffective psychosis. In a subgroup who had experienced trauma (N = 40), 12.5% had hallucinations with similar themes and content to their traumas, 45% had hallucinations in which the themes were the same but not the content, and 42.5% had no identifiable associations between their hallucinations and previously experienced trauma. Traumas rated as intrusive were significantly associated with hallucinations rated as intrusive, although intrusive hallucinations were not associated with traumas in general. The traumas most likely to be associated with hallucinations were sexual abuse and bullying.

Accidents↗

PubMed2005

Causes of unexpected death in patients with multiple sclerosis: a forensic study of 50 cases.

To determine the cause of death (as a result of neurologic or nonneurologic complications or accidents) in patients with multiple sclerosis (MS), we reviewed the autopsies of 50 subjects with MS from the Office of the Chief Medical Examiner of Maryland (OCME) between 1982 and 2004. The series included 32 females and 18 males (mean age, 45.8 years; range, 25-69 years) and the causes of death were classified into 3 categories: (A) neurologic complication directly related to MS; (B) nonneurologic complications or other medical causes; and (C) accidents, etc. Of the 50 cases, in 43 there was a history of MS, but in 7 subjects there was not, and the diagnosis was established by neuropathologic examination. In Group A, 21 (42%) cases, deaths were directly related to a neurologic complication; in Group B, 14 (28%) cases were related to the following nonneurologic and medical causes: ASCVD 9 (18%), metabolic disorder 1 (2%), pulmonary embolism 3 (6%), and bronchopneumonia 1 (2%); and in Group C, 15 (30%) cases, deaths were due to trauma, 9 (18%); intoxication, 5 (10%); and thermal injury, 1 (2%). Thus, among the 50 subjects, in 26, deaths occurred naturally; and in 24, from accidents, homicides, suicides, or undetermined causes. Pathologically, the majority of cases showed either chronic inactive (66.7%) or chronic active (15.6%) demyelinating lesions, mainly in the cerebral hemispheres. In some cases, it appears that demyelinating lesions, involving brain regions that regulate cardiorespiratory activity, could be considered as the immediate cause of death, but a large proportion appears to be due to other causes such as accidents and trauma. Thus, it seems likely that taking specific precautions could prevent some deaths in MS.

Adult↗

PubMed2005

Psychological investigation of the structure of paranoia in a non-clinical population.

BACKGROUND: Previous studies of paranoia have assessed only limited numbers of paranoid thoughts, and have not considered the experience from a multidimensional perspective or examined the relationship between different suspicious thoughts. AIMS: To assess a wide range of paranoid thoughts multidimensionally and examine their distribution, to identify the associated coping strategies and to examine social-cognitive processes and paranoia. METHOD: Six questionnaire assessments were completed by 1202 individuals using the internet. RESULTS: Paranoid thoughts occurred regularly in approximately a third of the group. Increasing endorsement of paranoid thoughts was characterised by the recruitment of rarer and odder ideas. Higher levels of paranoia were associated with emotional and avoidant coping, less use of rational and detached coping, negative attitudes to emotional expression, submissive behaviours and lower social rank. CONCLUSIONS: Suspiciousness is common and there may be a hierarchical arrangement of such thoughts that builds on common emotional concerns.

Adaptation, Psychological↗

PubMed2005

The prediction of hallucinatory predisposition in non-clinical individuals: examining the contribution of emotion and reasoning.

BACKGROUND: Emotion, especially anxiety, has been implicated in triggering hallucinations. Reasoning processes are also likely to influence the judgments that lead to hallucinatory experiences. We report an investigation of the prediction of hallucinatory predisposition by emotion and associated processes (anxiety, depression, stress, self-focused attention) and reasoning (need for closure, extreme responding). METHOD: Data were analysed from a questionnaire survey in a student population (N = 327). RESULTS: Higher levels of anxiety, self-focus, and extreme responding were associated with hallucinatory predisposition. Interactions between these three variables did not strengthen the predictive effect of each. Depression, stress, and need for closure were not found to be predictors of hallucinatory experience in the regression analysis. CONCLUSION: Emotional and reasoning processes may both need to be considered in the understanding of hallucinatory experience.

Adult↗

PubMed2005

Nonlinearities in source receptor relationships for sulfur and nitrogen compounds.

The relationship between emissions and deposition of air pollutants, both spatially and in time forms an important focus for science and for policy makers. In practice, this relationship may become nonlinear if the underlying processes change with time, or in space. Nonlinearities may also appear due to errors in emission or deposition data, and careful scrutiny of both data sources and their relationship provides a means of picking up such deficiencies. Nonlinearities in source receptor relationships for sulfur and nitrogen compounds in Europe have been identified in measurement data for the UK. In the case of sulfur, the dry deposition process has been shown to be strongly influenced by ambient concentrations of NH3, leading to substantial increases in deposition rate as SO2 concentrations decline and the ratio SO2/NH3 decreases. The field evidence extends to measurements over three different surfaces in three countries across Europe. A mechanistic understanding of the cause of this nonlinearity has been provided. Apparent nonlinearities also exist in the sulfur deposition field through the influence of shipping emissions. The effect is clear at west coast locations, where during a period in which land-based sulfur emissions declined by 50%, no significant decline in concentrations of SO(2-) in precipitation were observed. The sites affected are primarily the coastal regions of southwestern UK, where shipping sources contribute a substantial fraction of the deposited sulfur, but the effect is not detectable elsewhere. Full quantification of the spatially disaggregated emission and their changes in time will eliminate this apparent nonlinearity in the source-receptor data. For oxidized nitrogen emission and deposition in the UK, there is strong evidence of nonlinearity in the source-receptor relationship. The concentrations and deposition of NO(3-) in precipitation have declined little following a reduction in emissions of 45% during the period 1987 to 2001. The data imply a significant decrease in the average transport distance for oxidized nitrogen and most probably an increase in the average oxidation rate. However, the net effect of changes in aerosol chemistry due to changes in sulfur emissions and less competition for the main oxidants as a consequence of reductions in sulfur emission have not been separated. A quantitative explanation of the cause of this nonlinearity is lacking and the effects are therefore identified as an important uncertainty for the development of further protocols to control acidification, eutrophication and photochemical oxidants in Europe.

Air Movements↗

PubMed2005

The clinical laboratory practitioner.

OBJECTIVE: This study was designed to investigate potential areas of practice for the clinical laboratory scientist (CLS) and to propose a graduate curriculum to prepare the practitioner for an advanced level of practice. DESIGN: Meta-analysis of PharmD, physician assistant, physical therapy, and nurse practitioner curricula focusing on academic and clinical advanced practice was used to develop an educational model and curriculum for a professional doctorate in clinical laboratory science (CLS). MAIN OUTCOME MEASURE: (1) New educational model for CLS advanced practice; (2) A proposed curriculum for a Doctorate of Clinical Laboratory Science degree. RESULTS: A new curriculum model was adapted from established healthcare educational models. CONCLUSION: Although there is a need for a baccalaureate degree in CLS there is also a role for expanded education and responsibilities for CLS practitioners. The CLS Advanced Practitioner design focuses on moving students from the baccalaureate level to the doctoral level and prepares the individual to become an integral part of the healthcare team.

Curriculum↗

PubMed2004

Why do people with delusions fail to choose more realistic explanations for their experiences? An empirical investigation.

Delusions can be viewed as explanations of experiences,. By definition, the experiences are insufficient to merit the delusional explanations. So why have delusions been accepted rather than more realistic explanations? The authors report a study of alternative explanations in 100 individuals with delusions. Patients were assessed on the following criteria: symptom measures, the evidence for the delusions, the availability of alternative explanations, reasoning, and self-esteem. Three quarters of the patients did not report any alternative explanation for the experiences on which the delusions were based. These patients reported significantly more internal anomalous experiences and had a more hasty reasoning style than patients who did have alternative explanations available. Having doubt in a delusion, without an alternative explanation, was associated with lower self-esteem. Clinicians will need to develop plausible and compelling alternative accounts of experience in interventions rather than merely challenge patients' delusional beliefs.

Adult↗

PubMed2004

Negative symptoms, trauma, and autobiographical memory: an investigation of individuals recovering from psychosis.

Psychological research on negative symptoms in schizophrenia is scarce. The aim of this study was to explore the relationship between negative symptoms and trauma in individuals recovering from a psychotic illness. Specifically, the aim was to examine the association between negative symptoms and traumatic reactions to psychosis and to hospitalization. We were also interested in the association between traumatic reactions and autobiographical memory. The design was a cross-sectional investigation of 38 people recovering from functional psychotic illness. Hypotheses were examined using correlations between measures of negative symptoms, posttraumatic avoidance, and specificity of autobiographical retrieval. Negative symptoms were found to be significantly associated with avoidance of traumatic memories related to psychosis and hospitalization and with a lack of specificity in autobiographical recall. Further analysis showed that avoidance related to psychosis and low specificity in recall were significant predictors of negative symptoms. These data suggest that people who avoid traumatic memories of psychosis and hospitalization have more negative symptoms and retrieve fewer specific autobiographical memories. The possibility that negative symptoms may be reactive is explored, along with the implications for our theoretical and clinical understanding. The methodological limitations of the study and ideas for future research are discussed.

Adult↗

PubMed2004

Use of prostate specific antigen in the identification of semen in postmortem cases.

Over the past 20 years, the use of prostate specific antigen (PSA) as evidence of the presence of semen in forensic cases has been well established. In this study, we compared a commercially available immunoradiometric assay (IRMA) for the identification of PSA with the identification of spermatozoa in swabs obtained from the vagina of deceased females. There was agreement between the 2 methods in 67 of the 80 cases (84%), including 18 cases where both the PSA was positive and sperm were observed microscopically. The remaining cases had 1 positive result and 1 negative result. We concluded that although there was substantial agreement between the presence of sperm and a positive PSA, there were enough discrepancies between the 2 methods (16%) to justify the use of both methodologies, if possible, to make the determination of sexual activity prior to death.

Autopsy↗

PubMed2004

The distress experienced by voice hearers is associated with the perceived relationship between the voice hearer and the voice.

OBJECTIVES: To explore the relationship between distress and the perceptions that voice hearers have of their relationship with the voice they hear. We predicted that a dominant style of relating by the voice and a submissive and distancing style of relating by the voice hearer would be linked with distress. METHOD: Thirty people who were hearing voices took part in the study. Information was gathered about the characteristics of the voice-hearing experience, the level of distress experienced in relation to the voice, the relationship between the voice hearer and the voice, and level of depression. RESULTS: The tendency for the voice to relate in a dominating, insulting manner and the tendency of individuals to react with suspicion and lack of communication with the voice were uniquely associated with distress. CONCLUSIONS: Appraisals of the relationship between the voice and voice hearer made by voice hearers are associated with differing emotional responses to voices. Clinical assessments of people who have distressing voices may be enhanced by a detailed consideration of the sort of relationship that exists between the client and their voice.

Adult↗

PubMed2003

Ecological effects of sulfur dioxide, fluorides, and minor air pollutants: recent trends and research needs.

The regulation of the emissions of 'traditional' primary air pollutants (fluorides, sulfur dioxide) has changed the pattern of exposure of ecological systems, with greatly reduced exposure close to sources, but with a smaller effect in some remote areas. Measurements show that recovery is occurring at some sites, in fresh water chemistry (reduced acidity) and in sensitive biota (sustainable fish populations). However, the pattern of change in exposure has not always been simply related to emission reductions. An understanding of responses to recent changes will improve our predictions of the response to future emission changes, both locally and globally. As exposure to 'traditional' pollutants is reduced, the potential for other pollutants to have effects becomes more evident. In the aqueous phase, we need to understand the role of soluble and suspended organics, but this also means explicit recognition of the possibility of phase exchange, and the role of photolytic reactions on plant, soil, and water surfaces. Do highly reactive free radicals in the atmosphere, formed by the action of sunlight on volatile organic compounds, have direct effects on plants? Organic compounds and heavy metals may be bioactive as gases and particles, but for many potentially toxic compounds, the experimental evidence for biotic response is very limited. To evaluate the potential effects of pollutants, we need to understand the pathways by which airborne pollutants enter and react within ecosystems. For vegetation, we have to consider bidirectional fluxes, and distinguish among uptake through stomata, through leaf surfaces, or through roots. There are several challenges for the future. (1) Can we devise experiments that permit exposure of vegetation to gases, particles, and/or aqueous pollutants at 'realistic' concentrations? (2) Can we include the potential interactions with photolytically derived free radicals, and the dynamics of exchange? (3) How do we allow for responses to pollutant mixtures, or the simultaneous exposure to pollutants in gas, particle, and aqueous phases? The recognition of the importance of the dynamic exchange of pollutants between phases will be the key to the development of effective experimental approaches to evaluating cause-effect relationships between pollutant mixtures and ecosystem responses.

Air Pollutants↗

PubMed2003

Tentative identification of novel oxycodone metabolites in human urine.

Oxycodone is a semisynthetic codeine derivative that has been used both as an analgesic and antitussive. In the mid 1990s, OxyContin was introduced as a slow-release formulation of oxycodone for use in patients with moderate to severe chronic pain from such ailments as arthritis, vertebral disc disease, and cancer. Doctors wrote 6.9 million prescriptions for OxyContin from May 2000 through May 2001. Thus, it is no surprise that hospitals and medical examiners' offices across the country have seen an increasing number of admissions and deaths resulting from oxycodone abuse and overdose. The laboratory identifies oxycodone as part of its routine abused and therapeutic drug-testing procedures. Routine gas chromatographic analysis of bile or urine in many of these cases revealed unidentified peaks in the region of oxycodone that appeared to be oxycodone metabolites. In humans, the only documented metabolites of oxycodone are oxymorphone and N-desmethyloxycodone (noroxycodone). This study attempts to characterize these compounds as "presumptive" metabolites based on circumstantial evidence from known metabolic pathways of oxycodone in other species, as well as of other opiates and narcotic analgesics.

Analgesics, Opioid↗

PubMed2003

Can virtual reality be used to investigate persecutory ideation?

The use of virtual reality permits individuals' reactions to standard controlled environments to be studied. It may therefore provide a means for understanding the interpretations of experience relevant to clinical disorders. The use of this technology for understanding persecutory ideation has not been investigated. A pilot study was undertaken to examine whether individuals have persecutory thoughts about virtual reality characters under controlled conditions and if there are factors that predict the occurrence of such thoughts.Twenty-four nonclinical participants entered a neutral virtual environment that contained computer-generated people. The participants completed dimensional assessments of items related to psychiatric symptoms and their thoughts about the virtual characters. Positive views about the virtual characters were common. However, a number of participants had ideas of reference and ideas of persecution about the virtual characters. Individuals who had persecutory thoughts about the virtual characters had significantly higher levels of interpersonal sensitivity and anxiety. The study provides direct evidence that individuals attribute mental states to virtual reality characters. Important for the study of clinical phenomena, some individuals have thoughts of a persecutory nature about virtual characters. Additionally, the findings indicate that feelings of interpersonal vulnerability and anxiety may directly contribute to the development of persecutory ideation in response to essentially neutral contexts. Virtual reality may prove to be a valuable methodology for developing an understanding of persecutory ideation.

Adult↗