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Biomedical subjects

C Jackson

Publications and source records attributed to C Jackson.

At least 19 recordsLinked to original sources
PubMed2001

A measurement of the cosmological mass density from clustering in the 2dF Galaxy Redshift Survey.

The large-scale structure in the distribution of galaxies is thought to arise from the gravitational instability of small fluctuations in the initial density field of the Universe. A key test of this hypothesis is that forming superclusters of galaxies should generate a systematic infall of other galaxies. This would be evident in the pattern of recessional velocities, causing an anisotropy in the inferred spatial clustering of galaxies. Here we report a precise measurement of this clustering, using the redshifts of more than 141,000 galaxies from the two-degree-field (2dF) galaxy redshift survey. We determine the parameter beta = Omega0.6/b = 0.43 +/- 0.07, where Omega is the total mass-density parameter of the Universe and b is a measure of the 'bias' of the luminous galaxies in the survey. (Bias is the difference between the clustering of visible galaxies and of the total mass, most of which is dark.) Combined with the anisotropy of the cosmic microwave background, our results favour a low-density Universe with Omega approximately 0.3.

Journal Article↗
PubMed2001

Open-reading-frame sequence tags (OSTs) support the existence of at least 17,300 genes in C. elegans.

The genome sequences of Caenorhabditis elegans, Drosophila melanogaster and Arabidopsis thaliana have been predicted to contain 19,000, 13,600 and 25,500 genes, respectively. Before this information can be fully used for evolutionary and functional studies, several issues need to be addressed. First, the gene number estimates obtained in silico and not yet supported by any experimental data need to be verified. For example, it seems biologically paradoxical that C. elegans would have 50% more genes than Drosophilia. Second, intron/exon predictions need to be tested experimentally. Third, complete sets of open reading frames (ORFs), or "ORFeomes," need to be cloned into various expression vectors. To address these issues simultaneously, we have designed and applied to C. elegans the following strategy. Predicted ORFs are amplified by PCR from a highly representative cDNA library using ORF-specific primers, cloned by Gateway recombination cloning and then sequenced to generate ORF sequence tags (OSTs) as a way to verify identity and splicing. In a sample (n=1,222) of the nearly 10,000 genes predicted ab initio (that is, for which no expressed sequence tag (EST) is available so far), at least 70% were verified by OSTs. We also observed that 27% of these experimentally confirmed genes have a structure different from that predicted by GeneFinder. We now have experimental evidence that supports the existence of at least 17,300 genes in C. elegans. Hence we suggest that gene counts based primarily on ESTs may underestimate the number of genes in human and in other organisms.

Animals↗
PubMed2001

An evaluation approach for a new paradigm--health care integration.

This paper explores an approach to the implementation and evaluation of integrated health service delivery. It identifies the key issues involved in integration evaluation, provides a framework for assessment and identifies areas for the development of new tools and measures. A proactive role for evaluators in responding to health service reform is advocated.

Delivery of Health Care, Integrated↗
PubMed2001

Barriers to help seeking in people with urinary symptoms.

BACKGROUND: Urinary incontinence is a common problem but, for those experiencing significant clinical symptoms, help seeking has been reported to be as low as 20%. As many of these people could be helped by simple interventions, there is a clear need to identify barriers to help seeking and develop interventions to overcome these barriers. OBJECTIVES: This study explores help-seeking behaviour in people with urinary symptoms such as leakage, frequency, nocturia and urgency in order to identify barriers to service use. METHOD: Thirty-one people who either had agreed to treatment as part of an intervention study or who were receiving treatment at a hospital out-patient clinic for their urinary problems took part in unstructured, taped interviews. Respondents were questioned about their views on help seeking for urinary problems and their personal experiences of consultations. The data were transcribed, coded and thematic analysis carried out. RESULTS: The most common theme to emerge was a lack of knowledge of the condition and of available treatments. Urinary symptoms frequently were considered a normal part of ageing or childbirth, or it was felt that these types of symptoms were inappropriate for medical intervention. Older people were not only more likely to accept symptoms but were also less likely to want to bother their GP. Patients did not always communicate their concerns about urinary symptoms to their GP, through either embarrassment or misconceptions of what is a 'medical problem'. CONCLUSIONS: There is a clear need for health education and health promotion in this area. Future work should explore professionals' knowledge and views of these types of conditions with the aim of providing guidelines for management in primary care.

Adult↗
PubMed2001

Cytokine networking in lungs of immunocompetent mice in response to inhaled Aspergillus fumigatus.

Cytokine networking in the lung in response to inhaled Aspergillus fumigatus was assessed using a murine model of primary pulmonary aspergillosis in immunocompetent Crl:CF-1 mice. Inhalation of virulent A. fumigatus (6 x 10(6) CFU) resulted in the induction of interleukin 18 (IL-18), tumor necrosis factor alpha (TNF-alpha), IL-12, and gamma interferon (IFN-gamma) protein in bronchoalveolar lavage fluid and/or lung tissue. Induction of immunoreactive IL-18 preceded induction of TNF-alpha protein, which preceded induction of immunoreactive IL-12 and IFN-gamma. Real-time reverse transcriptase (RT) PCR analysis of infected lung tissue demonstrated that induction of IL-18 protein also preceded induction of pulmonary TNF-alpha, IL-12, and IFN-gamma mRNAs. Mice were subsequently treated with cytokine-specific neutralizing monoclonal antibodies (MAbs) to the IL-18 receptor (anti-IL-18R MAb), TNF-alpha (anti-TNF-alpha MAb), IL-12 (anti-IL-12 MAb), and/or IFN-gamma (anti-IFN-gamma MAb), and effects on intrapulmonary cytokine activity and growth of A. fumigatus were assessed in infected lung homogenates. Simultaneous neutralization of IL-12 and IL-18 resulted in decreased levels of immunoreactive TNF-alpha, while neutralization of IL-18, TNF-alpha, or IL-12 alone or of IL-18 and IL-12 together resulted in decreased levels of immunoreactive IFN-gamma. Simultaneous neutralization of IL-12 and IL-18 or neutralization of TNF-alpha alone or in combination with IL-12, IL-18, or IFN-gamma also resulted in a significant increase in A. fumigatus CFU in lung tissue. Taken together, these results demonstrate that endogenous IL-18, IL-12, and TNF-alpha, through their modulatory effects on both intrapulmonary cytokine activity and growth of A. fumigatus, play key roles in host defense against primary pulmonary aspergillosis.

Adjuvants, Immunologic↗
PubMed2000

Induction of psychogenic nonepileptic seizures without placebo.

The diagnosis of psychogenic nonepileptic seizures (PNES) can only be made with EEG-video monitoring. The authors describe a provocative technique without placebo. Patients with a clinical suspicion for PNES underwent an activation procedure using suggestion, hyperventilation, and photic stimulation. Of 19 inductions performed, 16 (84%) were successful in inducing the habitual episode. The authors' technique had a sensitivity comparable to those using placebo (e.g., saline injection), but does not have disadvantages.

Adult↗
PubMed2000

Cellular radiosensitivity and complication risk after curative radiotherapy.

PURPOSE: To test for an association between in vitro fibroblast radiosensitivity and complication risk in a case-control study of breast cancer patients treated under standard conditions in a clinical trial of radiotherapy dose fractionation. PATIENTS AND METHODS: A cohort of patients participating in a randomised clinical trial of radiotherapy dose fractionation was selected on the basis of treatment-induced changes in the breast several years later. Thirty-nine cases with marked normal tissue changes were matched on several variables with 65 controls with no changes attributable to radiotherapy. Dermal fibroblast strains were established from duplicate skin biopsies, and clonogenic cell survival assays performed in triplicate after both high ( approximately 1.6 Gy/min) and low ( approximately 1 cGy/min) dose-rate irradiation. Laboratory studies were blind to patient identity, treatment outcome and radiotherapy schedule. RESULTS: Analysis of 1128 clonogenic survival curves confirmed significant inter-patient variation in fibroblast radiosensitivity as measured by clonogenic survival. However, no association between fibroblast radiosensitivity and the development of late radiotherapy normal tissue effects was detected. CONCLUSIONS: Inter-individual variation in cellular radiosensitivity may not be the main determinant of complication risk in patients undergoing radiotherapy for breast cancer. Other biological and technical factors may be more important in explaining the marked inter-patient differences in normal tissue damage evident several years after curative radiotherapy.

Case-Control Studies↗
PubMed2000

Neurotologic follow-up after radiation of posterior fossa tumors.

OBJECTIVE: Stereotactic radiation treatment, also known as gamma knife surgery or radiosurgery, has come into acceptance as a treatment alternative to surgical removal for posterior fossa tumors. The purpose of this article is to describe the role of the neurotologist in the optimal management of neurotologic complications after stereotactic radiation, as illustrated by five patients. STUDY DESIGN: Retrospective chart review. PATIENTS: Five patients who underwent stereotactic radiation of posterior fossa tumors. MAIN OUTCOME MEASURES: Presence or absence of neurotologic complications (tumor growth, hearing loss, imbalance/ataxia, vertigo, and facial paralysis) or neurosurgical complaints (facial numbness, motor weakness, headache, hydrocephalus, and subarachnoid cysts). RESULTS: Postradiation neurotologic complaints included vertigo, imbalance/ataxia, and progressive hearing loss in four of the five patients. Continued tumor growth occurred in two patients; two patients had no growth; in one patient the tumor became smaller. The complications of facial nerve paralysis, facial numbness, motor weakness, headache, hydrocephalus, cerebellar edema, and posterior fossa arachnoid cyst formation occurred less frequently. CONCLUSIONS: Stereotactic radiation of posterior fossa tumors can produce significant neurotologic problems. It is imperative that neurotologists remain involved in the follow-up care of patients with posterior fossa tumors to offer optimal treatment alternatives for the neurotologic disorders.

Aged↗
PubMed2000

Patient satisfaction with urodynamics: a qualitative study.

This qualitative study was undertaken to assess patients' views of the urodynamic investigation. The aim was to identify the dimensions important to patients in evaluating satisfaction with this type of procedure and ways in which care could be improved. Unstructured interviews were carried out by four trained interviewers with 21 people (17 female and 4 male) who had undergone the urodynamic investigation at various gynaecology, urology and continence outpatient clinics. The interviews were audio-taped and transcribed verbatim. The data was then coded and a thematic analysis carried out. The main theme to emerge was focused on patients' feelings about the procedure. This consisted of a combination of anxiety and embarrassment. Anxiety was because of fear of the unknown and embarrassment at the intimate nature of the procedure and lack of privacy. The interpersonal and communication skills of the health care professional were central in alleviating these negative feelings. The establishment of a friendly relationship based on equality and mutual respect and trust was important in preventing anxiety and embarrassment. A number of practical issues were identified that would contribute to improving the service for patients. It was found that nurses possessed all the attributes required to provide an effective service and recommendations were made that nurses specializing in continence care should take a more active role in urodynamic investigations.

Adult↗
PubMed2000

Royal Australian College of Ophthalmologists and Royal Australian College of General Practitioners National GP Eye Skills Workshops: colleges and divisions reskilling general practice.

PURPOSE: Little formal eye skills training has historically been available to Australian general practitioners at undergraduate or postgraduate levels. The development of the National GP Eye Skills Workshop was a joint initiatve of the Royal Australian Colleges of General Practice and Ophthalmology, to enhance the skills of Australian general practitioners in a range of important ocular examination and procedural areas. METHODS: Workshops were run in eight Queensland Divisions of General Practice in 1998. Between two and 10 local ophthalmologists in each divisional area were involved ether in the workshop programme or in the recruitment of patients for the patient assessment module. Workshops were run on weekends and included modules on vision testing and disease screening in children and adults, ophthalmoscopy, assessment for glaucoma and diabetic retinopathy, incision of chalazions, removal of corneal foreign bodies, ocular first aid, implementing eye assessment in busy general practice, and a patient assessment clinic. A questionnaire was administered which was comprised of sections relating to the format of the workshop, new skills and concepts learnt, learning exceptions, and perception of future ability to treat/scan/assess for eye conditions in general practice. The questionnaire was completed by 91% of participants. RESULTS: Participants strongly supported the impact of the workshop on their ability to detect and treat eye problems in their practices, and refer where appropriate to an ophthalmologist. They also rated highly all individual aspects of the programme in terms of impact on their delivery of general practitioner eye care. CONCLUSIONS: The results illustrate the comprehensive success of the workshop programme in format, content, relevance and delivery.

Adult↗
PubMed2000

Immunomodulatory role of endogenous interleukin-18 in gamma interferon-mediated resolution of replicative Legionella pneumophila lung infection.

The in vivo role of endogenous interleukin-18 (IL-18) in modulating gamma interferon (IFN-gamma)-mediated resolution of replicative Legionella pneumophila lung infection was assessed using a murine model of Legionnaires' disease. Intratracheal inoculation of A/J mice with virulent bacteria (10(6) L. pneumophila organisms per mouse) resulted in induction of IL-18 protein in bronchoalveolar lavage fluid (BALF) and intrapulmonary expression of IL-18 mRNA. Real-time quantitative RT-PCR analysis of infected lung tissue demonstrated that induction of IL-18 in BALF preceded induction of IL-12 and IFN-gamma mRNAs in the lung. Blocking intrapulmonary IL-18 activity by administration of a monoclonal antibody (MAb) to the IL-18 receptor (anti-IL-18R MAb) prior to L. pneumophila infection inhibited induction of intrapulmonary IFN-gamma production but did not significantly alter resolution of replicative L. pneumophila lung infection. In contrast, blocking endogenous IL-12 activity by administration of anti-IL-12 MAb) alone or in combination with anti-IL-18R MAb inhibited induction of intrapulmonary IFN-gamma and resulted in enhanced intrapulmonary growth of the bacteria within 5 days postinfection. Taken together, these results demonstrate that IL-18 plays a key role in modulating induction of IFN-gamma in the lung in response to L. pneumophila and that together with IL-12, IL-18 regulates intrapulmonary growth of the bacteria.

Animals↗
PubMed2000

Characterization of a novel outer membrane hemin-binding protein of Porphyromonas gingivalis.

Porphyromonas gingivalis is a gram-negative, anaerobic coccobacillus that has been implicated as a major etiological agent in the development of chronic periodontitis. In this paper, we report the characterization of a protein, IhtB (iron heme transport; formerly designated Pga30), that is an outer membrane hemin-binding protein potentially involved in iron assimilation by P. gingivalis. IhtB was localized to the cell surface of P. gingivalis by Western blot analysis of a Sarkosyl-insoluble outer membrane preparation and by immunocytochemical staining of whole cells using IhtB peptide-specific antisera. The protein, released from the cell surface, was shown to bind to hemin using hemin-agarose. The growth of heme-limited, but not heme-replete, P. gingivalis cells was inhibited by preincubation with IhtB peptide-specific antisera. The ihtB gene was located between an open reading frame encoding a putative TonB-linked outer membrane receptor and three open reading frames that have sequence similarity to ATP binding cassette transport system operons in other bacteria. Analysis of the deduced amino acid sequence of IhtB showed significant similarity to the Salmonella typhimurium protein CbiK, a cobalt chelatase that is structurally related to the ATP-independent family of ferrochelatases. Molecular modeling indicated that the IhtB amino acid sequence could be threaded onto the CbiK fold with the IhtB structural model containing the active-site residues critical for chelatase activity. These results suggest that IhtB is a peripheral outer membrane chelatase that may remove iron from heme prior to uptake by P. gingivalis.

Amino Acid Sequence↗
PubMed1999

Opioid peptide receptor studies. 10. Nor-BNI differentially inhibits kappa receptor agonist-induced G-protein activation in the guinea pig caudate: further evidence of kappa receptor heterogeneity.

There is strong evidence supporting the existence of multiple kappa receptors. Previous studies proposed that U69,593 and (+)-tifluadom act on different kappa receptor subtypes, kappa(1) (kappa(1)) and kappa(2) (kappa(2)), respectively. In this study, we investigated the effects of the kappa selective antagonist nor-binaltorphimine (Nor-BNI) on U69,593- and (+)-tifluadom-induced receptor-mediated stimulation of [(35)S]-GTP-gamma-S binding in the guinea pig caudate. The IC(50) value of Nor-BNI in the presence of a stimulating concentration of U69,593 (1 microM) was 0.19+/-0.02; while the IC(50) for Nor-BNI in the presence of (+)-tifluadom (1 microM) was 13.9+/- 1.62 nM. The mu-opioid receptor antagonist CTAP (10,000 nM) significantly reduced (+)-tifluadom-stimulated [(35)S]-GTP-gamma-S binding in rat brain sections and guinea pig brain membranes, indicating that (+)-tifluadom has mu agonist activity. Under conditions in which the mu agonist activity of (+)-tifluadom was blocked by 1000 nM CTAP the Ki value for Nor-BNI for inhibition of U69,593-stimulated [(35)S]-GTP-gamma-S binding was 0.036+/-.004 nM, whereas, its Ki value for the (+)-tifluadom-stimulated [(35)S]-GTP-gamma-S binding was 0.27+/-.015 nM. These results suggest that (+)-tifluadom and U69,593 activate pharmacologically different receptors. This study provides functional evidence in support of kappa receptor heterogeneity.

Animals↗
PubMed1999

Pulmonary evaluation and prevalence of non-invasive ventilation in patients with amyotrophic lateral sclerosis: a multicenter survey and proposal of a pulmonary protocol.

In order to evaluate the current standard of care for the management of respiratory failure in patients with amyotrophic lateral sclerosis (ALS), a questionaire was mailed to the Medical Directors of 48 multidisciplinary ALS centers in the United States. Twenty centers reported information on 2357 patients, mean of 124 patients per center. Pulmonary function tests were performed at each visit in 17/20 institutions. Arterial blood gases, maximal expiratory pressures and maximal inspiratory pressures were followed in three centers and serum chloride was monitored in only four centers. The use of non-invasive ventilation (NIV) was extremely variable (range 0-50%) and included 360 patients (15%). The majority of centers used symptoms/signs of hypoventilation and worsening forced vital capacity (FVC) to initiate NIV with no established protocol. A FVC between 20 and 40% was used by most centers to initiate NIV. Due to great variability in the approach to monitoring pulmonary function among ALS centers and the modest effects of current medications to slow disease progression, we propose the use of a structured protocol which can prospectively study the role of NIV in prolonging survival and improving quality of life.

Amyotrophic Lateral Sclerosis↗