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Biomedical subjects

R Ward

Publications and source records attributed to R Ward.

At least 19 recordsLinked to original sources
PubMed2001

mtDna and the islands of the North Atlantic: estimating the proportions of Norse and Gaelic ancestry.

A total of 1,664 new mtDNA control-region sequences were analyzed in order to estimate Gaelic and Scandinavian matrilineal ancestry in the populations of Iceland, Orkney, the Western Isles, and the Isle of Skye and to investigate other aspects of their genetic history. A relative excess of private lineages in the Icelanders is indicative of isolation, whereas the scarcity of private lineages in Scottish island populations may be explained by recent gene flow and population decline. Differences in the frequencies of lineage clusters are observed between the Scandinavian and the Gaelic source mtDNA pools, and, on a continent-wide basis, such differences between populations seem to be associated with geography. A multidimensional scaling analysis of genetic distances, based on mtDNA lineage-cluster frequencies, groups the North Atlantic islanders with the Gaelic and the Scandinavian populations, whereas populations from the central, southern, and Baltic regions of Europe are arranged in clusters in broad agreement with their geographic locations. This pattern is highly significant, according to a Mantel correlation between genetic and geographic distances (r=.716). Admixture analyses indicate that the ancestral contributions of mtDNA lineages from Scandinavia to the populations of Iceland, Orkney, the Western Isles, and the Isle of Skye are 37.5%, 35.5%, 11.5%, and 12.5%, respectively.

Atlantic Islands↗
PubMed1992

Interactive video: an analysis of its value to nurse education.

This paper attempts to explain the emerging technology of interactive video and examine its possible place in nursing education. A brief description of the media is given with an exploration of the educational theory and justification underlying its use. A range of approaches to the evaluation of the technology itself and software available are given, which examine advantages and disadvantages for individual learners and for an organisation considering investment in this area. The possible role of interactive video in nurse education is discussed and a recommendation given that nurse educators need to keep up-to-date with developments in this type of educational technology and develop software suitable for the needs of nurses, rather than having to use packages developed for other purposes which have limited application for nursing.

Computer-Assisted Instruction↗
PubMed1992

Evidence of GABA-immunopositive neurons in the dorsal part of the lateral geniculate nucleus of reptiles: morphological correlates with interneurons.

The distribution and staining pattern of gamma-aminobutyric acid immunoreactivity have been examined by both light and electron microscopy in the dorsal part of the lateral geniculate nucleus of three reptilian species: the turtle Chinemys reevesi, the lizard Ophisaurus apodus and the snake Vipera aspis. After perfusion of the animals with 1% paraformaldehyde and 1% glutaraldehyde and polyethyleneglycol embedding of the brains, the analysis of sections processed immunocytochemically with an anti-GABA antiserum has revealed a moderate-to-dense labeling of the neurons of the dorsal part of the lateral geniculate complex in these species. Labeled cell bodies are small-sized, either rounded or fusiform and the GABA-positive dendrites emerging from them are not preferentially oriented in any particular direction. Quantitative studies in Vipera indicate that GABA-positive neurons make up about 14% of the population of neurons of the dorsal part of the lateral geniculate nucleus. Electron microscopy of specimens treated by either pre- or post-embedding techniques has confirmed that these cells corresponded to neurons. No glial cells were ever observed to be immunopositive. These GABA-positive neurons, characterized by the presence of pleiomorphic synaptic vesicles localized either in their perikaryon or more often in presynaptic dendrites, established symmetrical synaptic contacts. In this case, the latter were involved both pre- and postsynaptically in serial and, more rarely, in triadic arrangements, a synaptic organization specific to interneurons. The involvement of such GABA-positive neurons in local circuits is discussed.

Animals↗
PubMed1992

Phase I study of BW12C in combination with mitomycin C in patients with advanced gastrointestinal cancer.

The effect of combining the oxyhemoglobin-modifying drug BW12C with mitomycin C was investigated in a Phase I study of 18 patients with advanced gastrointestinal cancer. The dose of BW12C was increased from 20 mg/kg to 50 mg/kg to modify the hemoglobin-oxygen saturation curve by up to 48%. The period of maximum modification was then prolonged for up to 3 hr by a maintenance infusion of 4-6 mg/kg/hr. Pharmacokinetics of BW12C and mitomycin C were performed in all patients. Peak levels of BW12C increased from 139 micrograms/ml to 378 micrograms/ml. Plasma half life was independent of dose, with an average of 3.3 hr. BW12C was well tolerated with no severe side effects. Three patients had objective tumour responses.

Adenocarcinoma↗
PubMed1992

Radiosensitivity testing of human malignant gliomas.

Radiotherapy remains the main treatment modality for patients with malignant gliomas and is the only treatment which significantly prolongs survival. Clonogenic and tetrazolium based colorimetric assays (MTT) of early passage cultures have been performed following 2 Gy doses of x-rays in order to determine if in vitro radiosensitivity is a factor in response to treatment. Of 47 biopsies received, 39 were established in primary culture. A value of surviving fraction to 2 Gy (SF2) was obtained in 85% of growth assays and 64% of clonogenic assays. The mean SF2 value for the MTT was 0.56 which was significantly higher than the 0.42 obtained for the clonogenic assay. There was, however, reasonable qualitative agreement in assessing relative radiosensitivity/radioresistance (r = 0.7). Mean SF2 values for grade 3 tumors were 0.52 (MTT) and 0.35 (clonogenic) as against mean SF2 values of 0.63 (MTT) and 0.47 (clonogenic assay) for grade 4 tumors. In 24 patients with adequate follow-up, no direct correlation was found between SF2 and survival, although mean SF2 values for patients surviving greater than 18 months was significantly less (p = 0.01) than patients surviving less than 18 months as determined by the MTT assay.

Brain Neoplasms↗
PubMed1992

Tumour concentrations of flavone acetic acid (FAA) in human melanoma: comparison with mouse data.

Flavone acetic acid (FAA) showed impressive effects against murine solid tumours but no activity in clinical studies. The mechanism of action in mice may involve damage to tumour vasculature or immunomodulation, and these effects may be species-specific. Alternatively, concentrations of FAA achieved in mouse tumours may be higher than in human tumours. It is important to resolve this issue since it raises important questions about the relevance of in vitro versus in vivo tumour screens and the development of FAA analogues. As part of a Cancer Research Campaign Phase II study of metastatic melanoma in which 8.4 g m-2 FAA was given as a 6 h infusion, six tumour biopsies were obtained from four patients. FAA tumour concentrations were determined by HPLC and compared with subcutaneous murine solid tumours within the same analytical laboratory. Tumour/plasma percentages (range 26-61%; mean +/- SD, 43.9 +/- 11.4%) were similar to those in mice, as was the area under the curve (AUC) extrapolated to infinity and the AUC above the putative activity threshold of 100 micrograms ml-1. We conclude that the exposure of drug-refractory human melanoma tissue to FAA was comparable to that of sensitive mouse tumours. This suggests that reduced penetration of FAA into human tumours is unlikely to explain the lack of antitumour activity observed in clinical studies and that differences in mechanism of action are predominant.

Adult↗
PubMed1992

The influence of carbogen breathing on tumour tissue oxygenation in man evaluated by computerised p02 histography.

Tumour tissue oxygenation has been measured in man during carbogen breathing (95% O2, 5% CO2) using a commercially available polarographic electrode system (Eppendorf p02 histograph). At least 200 tumour measurements in each of 17 patients with accessible tumours were taken before, and subsequently continuously after the commencement of carbogen breathing for periods of 10 to 30 min. In 12 out of 17 patients studied there was a significant increase in median tumour p02 during the first 10 min of carbogen breathing (range 9 to 1800%). There was an initial rapid increase in tumour p02 which was maintained until 8 to 12 min, but then decreased throughout the subsequent treatment period. Although there was a reduction in the proportion of point measurements < or = 10 mmHg in 11 out of 13 patients, during carbogen breathing, measured points of < or = 2.5 mmHg were only eliminated in three out of 11 tumours. The time course has implications for the planning of clinical trials utilising radiotherapy with carbogen breathing.

Carbon Dioxide↗
PubMed1992

Increased energy expenditure in cystic fibrosis is associated with specific mutations.

1. Measurements of resting metabolic rate were made by open-circuit indirect calorimetry in 78 unrelated cystic fibrosis patients and 30 healthy control subjects. The aims of this study were: (i) to determine the range of variability in resting metabolic rate in cystic fibrosis, (ii) to relate this to pulmonary function and body size, and (iii) to investigate the hypothesis that, in cystic fibrosis, genotype exerts a significant influence on energy requirements. 2. There was no significant difference in age or body weight between patients with cystic fibrosis and control subjects. Resting metabolic rates for control subjects fell within +/- 10% of predicted values. Fifty-nine per cent of patients with cystic fibrosis had elevated resting metabolic rates (i.e. greater than 111% of predicted). Genotype analysis divided the patients with cystic fibrosis into three groups: delta F508 homozygotes, delta F508 heterozygotes and others. Patients homozygous for the delta F508 allele had a significantly higher resting metabolic rate (121% of predicted, 95% confidence interval 116-126%), compared with other genotypes (P less than 0.005). 3. There were significant differences in pulmonary function between the groups (P less than 0.005). However, after adjustment of individual resting metabolic rates for differences in pulmonary function by using analysis of covariance, resting metabolic rates remained significantly higher for delta F508 homozygotes than for other genotypes (P less than 0.05). 4. We conclude that there is a significant contribution to resting metabolic rate in cystic fibrosis associated with specific mutations that is not explained by declining pulmonary function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

The IC50: an exactly defined measure of antibiotic sensitivity.

The concentration of gentamicin that inhibits the growth of half of an inoculum of Pseudomonas aeruginosa (IC50) was estimated by doing viable bacterial counts with varying concentrations of gentamicin and fitting a probit inhibition curve to the results. This is a more precisely defined measure than the MIC and its standard error is readily calculable.

Anti-Bacterial Agents↗
PubMed1992

Phlebotomine sandflies in Venezuela: review of the verrucarum species group (in part) of Lutzomyia (Diptera: Psychodidae) with description of a new species from Lara.

The series townsendi and verrucarum of the verrucarum species group of the phlebotomine genus Lutzomyia França are reviewed. Lutzomyia nadiae, new species, from the mountains of Yacambú, Lara State, is described. Distribution maps, illustrated keys, notes on medical importance, taxonomy, and ecology are presented for species in these series known from Venezuela.

Animals↗
PubMed1992

Quantitative computer analysis of the sounds of isolated motor unit action potentials.

To develop quantitative measures of motor unit action potential (MUAP) sounds, we correlated Fourier domain features of isolated, individual MUAPs with classic time domain measurements. There were moderate correlations between amplitude or duration measurements, and absolute low-frequency (39 to 234 Hz) energy and amplitude of the peak frequency, and high correlations between the composite time domain feature of amplitude x duration, and total energy, amplitude of the peak frequency, and absolute low-frequency energy. Polyphasic potentials have multiple peaks in the magnitude component of the Fourier transform. Phase information appears to convey the "crisp" sound of MUAPs close to the recording electrode. The clinical description of "large" or "small" MUAPs by sound is likely based on absolute low-frequency energy, and incorporates both amplitude and duration information. We conclude that features of isolated MUAPs may be analyzed in the Fourier domain, and that they correlate closely with traditionally used measures of known diagnostic significance. The sound of the EMG used by clinical electromyographers is amenable to quantitative analysis.

Action Potentials↗
PubMed1992

A reconsideration of the primary visual system of the turtle Emys orbicularis.

The retinocerebral projections of Emys orbicularis were investigated by means of [3H]-proline or HRP, administered by intraocular injection. Two newly-hatched, two juvenile and seven adult specimens were examined. The results reveal contralateral retinal projections to fifteen sites: two in the hypothalamus (the nuclei suprachiasmaticus and periventricularis), five in the thalamus (the nuclei ovalis, geniculatus lateralis ventralis, geniculatus laleralis dorsalis, dorsolateralis anterior and ventrolateralis), five in the pretectal region (the nuclei geniculatus pretectalis, opticus pretectalis ventrolateralis, lentiformis mesencephali, posterodorsalis and griseus tectalis), two in the optic tectum (the stratum opticum and the stratum fibrosum et griseum superficiale), and one in the tegmentum (the nucleus opticus tegmenti). Ipsilateral projections to nine of these sites at thalamic, pretectal, tectal and tegmental levels, while weak, could be clearly demonstrated. These results differ considerably from those obtained in a previous investigation using a Nauta-paraffin technique; it is suggested that the differences are due to limitations of the latter technique. A review of the existing literature on the Chelonian primary visual system reveals considerable terminological diversity, and a standard nomenclature for the primary visual centres of turtles is proposed.

Afferent Pathways↗
PubMed1992

Physiological mechanisms for metalloproteinase activation.

The activation of procollagenase and prostromelysin by mechanisms that might be functional in vivo has been investigated. Studies with cell monolayers plated onto collagen films have indicated key roles for plasmin and TIMP in these processes. Prostromelysin activation could be rapidly effected by fibroblast monolayers in the presence of plasminogen, with identical kinetics to plasminogen-streptokinase generated plasmin. Procollagenase activation by plasmin was shown to be poor, although an M(r) shift of 11,000 occurred. Activation was enhanced ten-fold by the presence of active stromelysin even at a very low molar ratio. A tumour cell line secreting procollagenase but not stromelysin was found to be dependent upon the addition of both stromelysin and plasminogen to effect degradation of collagen films. Biochemical studies of metalloproteinase activation were carried out using other purified proteinases synthesized by connective tissue cells including endopeptidase 24.11, endopeptidase-2, cathepsin B and cathepsin L. None was a particularly effective activator relative to plasmin, but cathepsin B was shown to activate stromelysin. By use of both cell model systems and biochemical studies of purified enzymes we have found that the role of plasmin as the major metalloproteinase activator in normal connective tissue cells remains unchallenged.

Amino Acid Sequence↗
PubMed1992

Nurse staffing levels and skill mix in accident and emergency departments.

This paper examines the history of nurse staffing and skill mix in accident and emergency (A&E) departments, and reports results from a study which examines numbers of staff and relates this to numbers of patients and organisation of work in A&E departments throughout one region. The types of procedures undertaken by nurses and the qualifications they held are also analysed. Conclusions about present variations in staffing in A&E departments are drawn, with recommendations for further study.

Emergencies↗
PubMed1992

[Behavioral asymmetry in BALB/cCF mice with corpus callosum abnormalities].

The possible homology between anomalies of the corpus callosum in mice and in humans remains questionable. The small number of existing behavioural studies in mice have not shown effects, at the behavioural level, of the absence or reduction in size of the corpus callosum. We therefore examined the development, during the first 3 weeks of postnatal life, of a number of simple reflex and integrative responses in the members of a sample of 101 BALB/cCF mice; at autopsy carried out at 50 days of age, 29 mice showed anomalies of the corpus callosum (total absence or an area less than 0.75 mm2). Asymmetry of the development of these responses was measured either as the proportion of animals showing asymmetrical appearance of responses on the left and right sides, and as the delay between appearances on the left and right sides in "asymmetrical" mice. Both measures decreased over the first 15 postnatal days, at the same rate in normal and abnormal mice; in each case the decrease is better described by a second-order, quadratic, function than by a simple linear function. We therefore conclude that the integrity of the corpus callosum is not necessary for the normal maturation of sensorimotor behaviour in mice, and suggest that this conclusion may possibly be explained by the relatively recent appearance of mice in the mammalian radiation.

Agenesis of Corpus Callosum↗