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Biomedical subjects

R Ward

Publications and source records attributed to R Ward.

At least 109 records · Page 6Linked to original sources
PubMed1998

The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients.

The Ontario Prehospital Advanced Life Support Study represents the largest prehospital study yet conducted, worldwide. This study will involve more than 25,000 cardiac arrest, trauma, and critically ill patients over an 8-year period. The study will evaluate the incremental benefit of rapid defibrillation and prehospital Advanced Cardiac Life Support measures for cardiac arrest survival and the benefit of Advanced Life Support for patients with traumatic injuries and other critically ill prehospital patients. This article describes the OPALS study with regard to the rationale and methodology for cardiac arrest patients.

Cost-Benefit Analysis↗
PubMed1998

Resilience of anthropometric data assembly strategies to imposed error.

The aim of this study was to examine strategies for selecting a criterion value during anthropometric data assembly and their resilience to imposed error. Sixty-seven women aged 16-60 years were subjected to three separate series of measurements, which included six skinfolds and three girths. A random error term was added to the first of the three series of measurements to produce a pseudo-series containing error, termed the 'erroneous replicated series'. Five strategies were then used to determine the criterion value of each of the replication series: the first measurement, the mean of the first two measurements, the mean of all three measurements, the mean of the closest two measurements and the median of the three measurements. The technical error between the criterion values of the true and the flawed replication series for each of the selection strategies was calculated. We found that, for five of the skinfolds and all of the girths, the median value provided the smallest technical error of measurement between the criterion values for the true and erroneous replication series. We conclude that the strategy of selecting the median of three measurements is the most resilient to imposed error.

Adolescent↗
PubMed1998

Survey of resistance of herpes simplex virus to acyclovir in northwest England.

Acyclovir (ACV) has been used for more than 15 years in the management of herpes simplex virus (HSV) and varicella-zoster virus (VZV) disease. The present survey was undertaken to assess the level of ACV resistance in the population. More than 2,000 HSV isolates from both immunocompetent and immunocompromised patients in northwest England were collected over a 2-year period and tested for sensitivity to ACV. These studies suggested a prevalence of resistance of approximately 0.1 to 0.6% in immunocompetent individuals, with no apparent difference in prevalence between treated and untreated groups. In line with previous studies, the prevalence of resistance in treated immunocompromised individuals was approximately 6%.

Acyclovir↗
PubMed1998

Serotype specificity of the neutralizing-antibody response induced by the individual surface proteins of rotavirus in natural infections of young children.

The relative contribution of the rotavirus surface proteins, VP4 and VP7, to the induction of homotypic as well as heterotypic neutralizing antibodies (NtAbs) in natural infections was studied. The NtAb titers of paired sera from 70 infants with serologically defined primary rotavirus infections were determined with a panel of rotavirus reassortants having one surface protein from a human rotavirus (serotypes G1 to G4 for VP7 and P1A and P1B for VP4) and the other surface protein from a heterologous animal rotavirus strain. A subset of 37 children were evaluated for epitope-specific antibodies to the two proteins by an epitope-blocking assay. The infants were found to seroconvert more frequently to VP4 than to VP7 by both methods, although the titers of the seroconverters were higher to VP7 than to VP4. Both proteins induced homotypic as well as heterotypic NtAbs. G1 VP7 frequently induced a response to both G1 and G3 VP7s, while G3 VP7 and P1A VP4 induced mostly homotypic responses.

Antibodies, Monoclonal↗
PubMed1997

Publish or perish.

Explore the source record for details and available documents.

Periodicals as Topic↗
PubMed1997

Differential glutamate immunoreactivity in glial cells of the retino-recipient layer of the viper optic tectum following retinal ablation. A quantitative EM immunogold study.

In normal conditions, retino-tectal terminals are densely glutamate-immunoreactive. During the degenerative process of these terminals, a significant increase of glutamate immunoreactivity has been exclusively observed in microglial cells. It is suggested that this phenomenon is consecutive to the synthesis of glutamate by these cells after their activation by degenerating optic terminals.

Animals↗
PubMed1997

Restricted attentional capacity within but not between sensory modalities.

Restrictions to attentional capacity are revealed by the interference that commonly results when two sensory inputs must be identified at the same time. To investigate this phenomenon within and between modalities, we presented streams of visual and/or auditory inputs, containing occasional targets to be identified and recalled. For two visual or two auditory streams, identification of one target produced a sustained reduction in the ability to identify a second, the period of interference lasting for several hundred milliseconds. Subjectively, when attention was assigned to one target it was temporarily unavailable for another. In contrast, there was no such time-locked interference between targets in different modalities. The results suggest a modality-specific restriction to concurrent attention and awareness; visual attention to one simple target does not restrict concurrent auditory attention to another.

Acoustic Stimulation↗
PubMed1997

Hypertension, serum angiotensinogen, and molecular variants of the angiotensinogen gene among Nigerians.

BACKGROUND: We evaluated the association among the M235T and T174M variants of the angiotensinogen (AGT) gene, plasma AGT, and hypertension status in a sample of Nigerians. METHODS AND RESULTS: Participants were selected from the extremes of the blood pressure distribution obtained from the population survey of 2509 men and women aged 25 to 74 years. Cases (hypertensive subjects) were individuals who had high blood pressure or were taking antihypertensive medication, and control subjects were individuals with low blood pressure who had never taken antihypertensive medication. We found a significant association between the M235T variant and plasma AGT level. Hypertensive subjects had higher plasma AGT levels compared with control subjects. The allele frequencies of the two variants were similar in the hypertensive patients and the control subjects. CONCLUSIONS: The consistent relationships observed between the M235T variant and the protein product and between plasma level of the protein and hypertension status in different ethnic groups provide some evidence for a biochemical mechanism linking DNA variation in the renin-angiotensin system with the hypertension phenotype.

Adult↗
PubMed1997

Attention to one or two features in left or right visual field: a positron emission tomography study.

In human vision, two features of the same object can be identified concurrently without loss of accuracy. Performance declines, however, when the features belong to different objects in opposite visual fields. We hypothesized that different positron emission tomography activation patterns would reflect these behavioral results. We first delineated an attention network for single discriminations in left or right visual field and then compared this with the activation pattern when subjects divided attention over two features of a single object or over two objects in opposite hemifields. When subjects attended to a single feature, parietal, premotor, and anterior cingulate cortex were activated. These effects were strongest in the right hemisphere and were, remarkably, unaffected by the direction of attention. In contrast, direction of attention affected occipital and frontal activity: right occipital and left lateral frontal activity were higher with attention to the left, whereas right lateral frontal activity was higher with attention to the right. When subjects identified two features of the same object, parietal, premotor, and anterior cingulate activity was enhanced further, predominantly this time in the left hemisphere. Again, there was no direction sensitivity. Direction-sensitive activation of lateral frontal cortex also was increased. Finally, when subjects divided their attention over opposite hemifields, activity in the direction-sensitive occipital and frontal regions fell to a level midway between those seen during exclusively leftward or rightward attention. Thus, the behavioral efficiency with which we attend to multiple features of a single peripheral object is paralleled by enhanced activity in structures generally active during peripheral selective attention as well as in structures that depend on the specific direction of attention, most notably lateral frontal cortex. In addition, in the direction-sensitive regions, dividing attention over hemifields causes a compromise pattern between the extreme levels obtained during unilateral attention.

Adolescent↗
PubMed1997

Immunocytochemical localization of dopamine and its synthetic enzymes in the central nervous system of the lamprey Lampetra fluviatilis.

The distribution of dopamine (DA)-containing cell bodies, fibers, and terminals in the brain and spinal cord of Lampetra fluviatilis was investigated by immunohistochemical means. In order to distinguish dopaminergic neurons from those using other catecholamines as the primary neurotransmitter, the distribution of dopamine-immunoreactive structures was compared to that of cell bodies, fibers, and terminals labelled with antibodies directed against the enzymes tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DBH), and phenylethanolamine-N-methyl transferase (PNMT). We define dopaminergic neurons as those that are simultaneously DA, TH, and AADC immunoreactive and at the same time DBH and PNMT nonreactive. The overall concentrations of dopamine, noradrenaline, and adrenaline and some of their metabolites were also measured via high-performance liquid chromatography of whole-brain extracts. Our results revealed the presence of 10 populations of dopaminergic neurons in the brain of the lamprey in the olfactory bulb, preoptic area, hypothalamus, rhombencephalon, and spinal cord. In addition, uniquely DA-immunoreactive neurons, in contact with the cerebrospinal fluid, were observed in the hypothalamus and spinal cord. Chromatography indicated that dopamine exists in considerably higher concentrations than noradrenaline in the lamprey brain, whereas adrenaline is absent, the latter finding being supported by our failure to observe any PNMT-immunoreactive cell bodies, fibers, or terminals. The dopaminergic system of the lamprey appears to share many features not only with that of other anamniotes but also with that of amniotes; however, as in teleosts, dopaminergic neurons in the midbrain corresponding to the substantia nigra, the retrorubral area, and the ventral tegmental area of other species do not exist in the lamprey.

Animals↗
PubMed1997

Cholecystokinin-like systems in the chameleon brain.

Immunohistochemical techniques were used to determine the distribution of cholecystokinin-8 (CCK8) immunoreactivity in the brain of the chameleon. In the telencephalon, CCK8-immunopositive somata were sparse and observed principally in the olfactory tubercle at the ventromedial edge of the rostral telencephalon and in the medial septum. Immunopositive fibers were observed mainly in the medial septal region and the ventral telencephalon. In the diencephalon, numerous CCK8-reactive fibers were densely concentrated in the periventricular region, the dorsolateral hypothalamus and the external zone of the median eminence. In the thalamus, labelled fibers were restricted to the peri-rotundal nuclei and the lateral part of the habenula. Immunoreactive cell bodies were observed in the medial part of the dorsal lateral geniculate nucleus, in the periventricular, ventral and lateral regions of the hypothalamus. In the mesencephalon, the densest accumulations of immunopositive fibers were observed in the area pretectalis, the periventricular gray matter, the medial tegmentum and the isthmus. Labelled neurons were observed in the deep, and occasionally intermediate, tectal layers and in the laminar nucleus of the torus semicircularis. In the rhombencephalon, labelled fibers were observed at the highest density in the central gray matter and the locus coeruleus; labelled somata were observed only in the nucleus of the tractus solitarius.

Animals↗
PubMed1997

Immuno-electron microscopy reveals that the excitotoxin quinolinate is associated with the plasma membrane in human peripheral blood monocytes/macrophages.

Quinolinate (QUIN), a tryptophan-derived excitotoxin, was localized ultrastructurally in human peripheral blood monocytes/macrophages (MO) by immuno-electron microscopy. A combined carbodiimide/glutaraldehyde/paraformaldehyde-based fixation procedure was developed for optimal retention of QUIN in the cell as well as minimal loss of ultrastructure; a silver-enhanced colloidal gold detection system was used for electron-microscopic analysis. Gold particles representing QUIN immunoreactivity were associated with the inner side of the plasma membrane in normal MO. The number of gold particles increased significantly when QUIN levels were elevated by treatment with its precursor kynurenine, but location of the gold particles remained essentially the same under this condition. Treatment with interferon-gamma increased the number of Golgi bodies, vacuoles and pseudopodia, reflecting the activated state of the cell. Significantly increased numbers of gold particles representing QUIN were detectable in approximately the same location as in the case of kynurenine treatment. Combined treatment with kynurenine and interferon-gamma maximally increased the number of gold particles at the periphery of the cell. The pseudopodia were intensely stained with gold particles, while they were not detectable in the inner part of the cytoplasm or in any other organelle even under this activated condition. The significance of the specific location of QUIN revealed in the present study and its relation to the release and subsequent actions of QUIN are discussed.

Cell Membrane↗
PubMed1997

Efficacy and safety of high-dose rhesus-human reassortant rotavirus vaccine in Native American populations.

OBJECTIVES: We compared the efficacy, safety, and immunogenicity of a rhesus rotavirus tetravalent vaccine (RRV-TV), a rhesus rotavirus monovalent (serotype 1) vaccine (RRV-S1), and placebo in healthy American Indian infants for two rotavirus seasons. STUDY DESIGN: Infants aged 6 to 24 weeks were enrolled in a randomized, double-blind efficacy study. Infants were orally administered RRV-TV (4 x 10(5) plaque-forming units per dose), RRV-S1 (4 x 10(5) plaque-forming units per dose), or placebo at 2, 4, and 6 months of age. Stools collected during episodes of gastroenteritis were tested for detection of rotavirus antigen. A total of 1185 infants received at least one dose of a study vaccine or placebo, and 1051 received all three doses according to the protocol. RESULTS: During the first year of surveillance, the estimates of vaccine efficacy (with 95% confidence interval) for preventing rotaviral gastroenteritis were 50% (26, 67) for RRV-TV and 29% (-1, 50) for RRV-S1. In this population only 6% of rotaviral gastroenteritis episodes among placebo recipients were associated with type G1 disease. For severe disease the estimates of vaccine efficacy were higher: 69% (29, 88) for RRV-TV and 48% (-4, 75) for RRV-S1. CONCLUSIONS: These data indicate that RRV-TV is moderately efficacious in preventing all episodes of gastroenteritis caused by rotavirus and is most efficacious against the severe disease characteristic of rotaviral illness.

Double-Blind Method↗
PubMed1997

Metastatic malignant mesothelioma presenting as colonic polyps.

A 66-year-old male engineer diagnosed with malignant pleural mesothelioma 4 years previously had thoracotomy, radiotherapy, and chemotherapy. He was followed regularly with chest computed tomography (CT) scan and had been asymptomatic. During one of his physical examinations, routine sigmoidoscopy showed incidental colonic polyps which were biopsied. Subsequently, recurrence of pleural mesothelioma and peritoneal involvement by mesothelioma was documented. Two of the polyps showed metastatic malignant mesothelioma in the lamina propia which strongly resembled adenocarcinoma histologically causing difficulty in making definitive diagnosis. Review of the literature disclosed no previously documented similar occurrence. This case shows the importance of clinical history and ancillary laboratory procedures such as immunohistochemistry and electron microscopy to avoid diagnostic pitfalls.

Adenocarcinoma↗
PubMed1997

Implications of computer networking and the Internet for nurse education.

This paper sets out the history of computer networking and its use in nursing and health care education, and places this in its wider historical and social context. The increasing availability and use of computer networks and the internet are producing a changing climate in education as well as in health care. Moves away from traditional face-to-face teaching with a campus institution to widely distributed interactive multimedia learning will affect the roles of students and teachers. The use of electronic mail, mailing lists and the World Wide Web are specifically considered, along with changes to library and information management skills, research methods, journal publication and the like. Issues about the quality, as well as quantity, of information available, are considered. As more and more organizations and institutions begin to use electronic communication methods, it becomes an increasingly important part of the curriculum at all levels, and may lead to fundamental changes in geographical and professional boundaries. A glossary of terms is provided for those not familiar with the technology, along with the contact details for mailing lists and World Wide Web pages mentioned.

Computer Communication Networks↗
PubMed1997

Enrichment of glutamate-like immunoreactivity in the retinotectal terminals of the viper Vipera aspis: an electron microscope quantitative immunogold study.

A post-embedding immunogold study was carried out to estimate the immunoreactivity to glutamate in retinal terminals, P axon terminals and dendrites containing synaptic vesicles in the superficial layers of the optic tectum of Vipera. Retinal terminals, identified following either intraocular injection of tritiated proline, horseradish peroxidase (HRP) or short-term survivals after retinal ablation, were observed to be highly glutamate-immunoreactive. A detailed quantitative analysis showed that about 50% of glutamate immunoreactivity was localized over the synaptic vesicles, 35.8% over mitochondria and 14.2% over the axoplasmic matrix. The close association of immunoreactivity with the synaptic vesicles could indicate that Vipera retino-tectal terminals may use glutamate as their neurotransmitter. P axon terminals and dendrites containing synaptic vesicles, strongly gamma-aminobutyric (GABA)-immunoreactive, were shown to be also moderately glutamate-immunoreactive, but two to three times less than retinal terminals. Moreover, in P axon terminals, the glutamate immunoreactivity was denser over mitochondria than over synaptic vesicles, possibly reflecting the 'metabolic' pool of glutamate, which serves as a precursor in the formation of GABA.

Animals↗