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Biomedical subjects

N A Watson

Publications and source records attributed to N A Watson.

At least 19 recordsLinked to original sources
PubMed2003

Filthy or fashionable? Young people's perceptions of smoking in the media.

Research has shown that the media over-estimates smoking rates and often associates smoking with favorable attributes or situations. Given that the media plays a large role in influencing youth culture, portrayal of smoking in the media is of concern. In order to explore young people's perceptions of smoking imagery in the media, 16 focus groups were conducted with 117 school students. Participants were asked to rate smoking images selected from audio-visual and print media, and to discuss their perceptions of these images. The results showed that young people perceived smoking in these media selections to be normal and acceptable. They identified with the stress-relieving and social aspects of smoking, despite being well aware of the harmful health effects. Its acceptability as part of a 'cool' image was also noted. Positive images of smoking in the media have the potential to down-play the serious health consequences of smoking by portraying it in a way that young people interpret as a normal part of everyday life. They may also encourage a more neutral or tolerant attitude towards smoking among young people and therefore act to counteract other health promotion efforts to reduce teenage smoking.

Adolescent↗
PubMed2001

Improved high resolution MR imaging for surface coils using automated intensity non-uniformity correction: feasibility study in the orbit.

This study examined the effects of a recently developed automated intensity non-uniformity correction on surface coil images using the orbit as an exemplar. Images were obtained using a standard head coil and a range of surface coils. Slices through the optic nerve head and cavernous sinus were subjected to the correction algorithm. Blind forced-choice rankings of the subjective image quality were performed. Quantitative measurements were taken of the similarity between vitreous humor at two depths from the coil, and of the conspicuity between orbital fat and temporalis muscle intensities. The combined qualitative ranks for corrected surface coil images were higher than for the equivalent uncorrected images in all cases. Intensity non-uniformity correction produced statistically significant improvements in orbital surface coil images, bringing their intensity uniformity in homogeneous tissue to the level of head coil images. The subjective quality of the corrected surface coil images was superior to head coil images, due to increased spatial resolution combined with improved signal to noise ratio across the image.

Algorithms↗
PubMed2000

The effect of hyperoxia on cerebral blood flow: a study in healthy volunteers using magnetic resonance phase-contrast angiography.

A small decrease in cerebral blood flow (approximately 10%) in response to 100% oxygen (O2) administration is well recognized. This observation was based on human volunteer studies, which employed a nitrous oxide washout method for the measurement of cerebral blood flow. Because this method is now appreciated to be subject to potential errors we have examined the cerebral blood flow response to 100% oxygen using a magnetic resonance imaging technique to quantify changes in carotid and basilar artery flow. The study, was performed in 12 normal male subjects aged 23-42 years. We report decreases in cerebral blood flow ranging from 9 to 31% with a mean value of over 20%. The decrease in cerebral blood flow was greater in seven young subjects (aged 23-26 years) with decreases in cerebral blood flow of 19.3-31.4% (mean 26.8%). In five older subjects (aged 32-42 years), decreases in CBF were smaller (mean 16. 2%). The administration of 100% O2 was accompanied by a small decrease in end-tidal CO2 (3.7-7.1%), insufficient to explain the changes in cerebral blood flow. We conclude that the decrease in cerebral blood flow in response to O2 administration is greater than previously described and appears to be greater in young adults.

Adult↗
PubMed1999

Ultrastructure of the eyes of the larva of Neoheterocotyle rhinobatidis (Platyhelminthes, Monopisthocotylea), and phylogenetic implications.

The oncomiracidium of Neoheterocotyle rhinobatidis (Monogenea, Monopisthocotylea, Monocotylidae) has two pairs of eyes, each eye with a lens and pigment cup. The anterior eyes have a single rhadomere; the posterior ones, two rhadomeres. Lenses are part of the pigment cup cells, as indicated by cytoplasmic connections between them and the pigment cups, and they are of mitochondrial origin because mitochondrial cristae are present in the periphery of the lenses. This is the first time that mitochondrial lenses have been shown to exist in a neodermatan. Such lenses may be a synapomorphy of a large taxon comprising the Neodermata and its turbellarian sister groups, or they may have evolved convergently in several not closely related groups as a result of strong selection pressure to find a suitable habitat or host.

Animals↗
PubMed1999

Mentoring today--the students' views. An investigative case study of pre-registration nursing students' experiences and perceptions of mentoring in one theory/practice module of the Common Foundation Programme on a Project 2000 course.

The study reported in this paper investigated the mentoring experiences and perceptions of pre-registration nursing students in one organization, on a theory/practice nursing module. It considered the extent to which students' understanding and expectations matched their actual experiences. Interviews were conducted with 35 students on a Common Foundation Programme, and 15 allocated mentors, using a semi-structured interview guide. These were done within the clinical setting of the wards on which the students were placed as part of their requirements for completion of the module. A distortion of the actual meaning of mentoring appears to be present because of the lack of clarity provided, both internally by organizations and by the English National Board (ENB) who have provided loose guidelines. The implications of this distortion are discussed. The application of a mentoring role in practice needs to be re-examined, with the provision of a clear structured guide internally and externally, with regard to the needs of students and staff who are expected to act as mentors. The study was small scale and cannot be generalized. Mentoring, however, is now widely used within pre-registration nursing education, even though it is generally considered that its use may not be appropriate. Follow-up studies need to be undertaken on an ongoing basis, to examine what actually happens in practice, and to consider ways of ensuring that the benefits for staff and students are enhanced.

Education, Nursing↗
PubMed1998

Symbioses in Amphipholis squamata (Echinodermata, Ophiuroidea, Amphiuridae): geographical variation of infestation and effect of symbionts on the host's light production.

Populations of the polychromatic and bioluminescent species Amphipholis squamata from eight locations were examined for internal and external symbionts. At three locations (two in the United Kingdom and one in Papua New Guinea), no symbionts were present, while four species were recovered from the remaining locations: Cancerilla tubulata and Parachordeumium amphiurae (copepods), Rhopalura ophiocomae (orthonectid) and an undescribed species of rhabdocoel turbellarian. No ophiuroid individual hosted more than one symbiont species, despite the presence of two or more within a population. Symbiont presence and prevalence varied with location, and with colour variety, but with no apparent pattern or trends. Light-production characteristics of the host were affected by the presence of all symbionts except C. tubulata. These effects, however, did not vary between colour varieties or between geographical locations, but were specific to the symbiont species: the presence of P. amphiurae resulted in enhanced intensity of light production, while that of R. ophiocomae and the turbellarian species resulted in reduced intensity. The kinetics of light production (time until maximum output) were altered only by the presence of the turbellarian. Changes in the light-production characteristics are discussed in relation to morphological, energetical and physiological effects of the symbioses.

Animals↗
PubMed1998

Supradiaphragmatic middle aorta syndrome--MR and angiographic imaging.

We describe the case of an asymptomatic 24-year-old man with hypertension who was investigated for aortic coarctation but found on MR scanning to have narrowing of the distal thoracic aorta. Stenosis of the thoracolumbar aorta--the Middle Aorta Syndrome--is rare and is usually found below the diaphragm. The MRI and angiographic findings are presented.

Adult↗
PubMed1997

The effect of post-injury spinal position on canal occlusion in a cervical spine burst fracture model.

STUDY DESIGN: The canal space of burst-fractured, human cervical spine specimens was monitored to determine the extent to which spinal position affected post-injury occlusion. OBJECTIVE: To test the null hypothesis that there is no difference in spinal canal occlusion as a function of spinal positioning for a burst-fractured cervical spine model. SUMMARY OF BACKGROUND DATA: Although previous studies have documented the effect of spinal positioning on canal geometry in intact cadaver spines, to the authors' knowledge, none has examined this relationship specifically in a burst fracture model. METHODS: Eight human cervical spine specimens (levels C1 to T3) were fractured by axial impact, and the resulting burst injuries were documented using post-injury radiographs and computed tomography scans. Canal occlusion was measured using a custom transducer in which water was circulated through a section of flexible tygon tubing that was passed through the spinal canal. Any impingement on the tubing produced a rise in fluid pressure that was monitored with a pressure transducer. Each spine was positioned in flexion, extension, lateral (and off-axis) bending, axial rotation, traction, and compression, while canal occlusion and angular position were monitored. Occlusion values for each position were compared with measurements taken with the spine in neutral position. RESULTS: Compared with neutral position, compression, extension, and extension combined with lateral bending significantly increased canal occlusion, whereas flexion decreased the extent of occlusion. In extension, the observed mechanism of occlusion was ligamentum flavum bulge caused by ligament laxity resulting from reduced vertebral body height. CONCLUSIONS: Increased compression of the spinal cord after injury may lead to more extensive neurologic loss. This study demonstrated that placing a burst-fractured cervical spine into either extension or compression significantly increased canal occlusion as compared with occlusion in a neutral position.

Biomechanical Phenomena↗
PubMed1997

Spermiogenesis and sperm ultrastructure in Troglocephalus rhinobatidis, Neoheterocotyle rhinobatidis and Merizocotyle australensis (Platyhelminthes, Monogenea, Monopisthocotylea, Monocotylidae).

The ultrastructural events of spermiogenesis and the ultrastructure of nature sperm of 3 species of monocotylid monogeneans are described. Two of these species, Troglocephalus rhinobatidis and Neoheterocotyle rhinobatidis are extremely similar in all the aspects studied, and their placement in separate subfamilies is questioned. Evidence is presented in both species for extensive distalward movement during spermiogenesis of an ornamented region associated with cortical microtubules, originally located in the zone of differentiation. Spermatids of Merizocotyle australis lack this ornamentation and the mature sperm also lacks cortical microtubules. Troglocephalus rhinobatidis exhibits the highest number (128) of spermatids in an isogenic group recorded for a flatworm to date. Sperm of all 3 species have 2 normal axonemes, shifted slightly relative to one another. Comparative data are presented on sperm and spermiogenesis of all monocotylids examined to date and the phylogenetic implications are discussed.

Animals↗
PubMed1996

Visually-evoked pattern and photomyoclonic responses in video game and television epilepsy: case reports.

This research paper reports a case study of two male photosensitive epileptic patients, aged 14 and 16 years old respectively, whose epileptic seizures were often triggered by the flickers from television and video games respectively. The 14-year old patient had no family history of epilepsy, while the 16 year old had a family history of epilepsy. A comprehensive electroencephalogram (EEG), including hyperventilation, intermittent photic stimulation (IPS) and pattern stimulation were carried out on them and EEG abnormalities including photoparoxysmal responses (PPR) and generalized myoclonic responses were evoked. A thorough analysis of the EEG morphology of the myclonic responses and the clinical manifestations showed evidence of two separate entitles of seizures namely: visually evoked pattern-myoclonic responses (PTMR) and visually evoked photomyoclonic responses (PMR). PTMR was independent of flash rate and occurred before a PPR and at the same time as the flash rate, while PMR occurred after the PPR and was dependent on flash rate. These findings suggest that "Video Game" epilepsy is probably a pattern sensitive epilepsy, electronic screen being the source of the triggering patterns; hence, the morphology and the family histories and the myoclonic phenomena differ from those of pure photosensitive epilepsy.

Adolescent↗
PubMed1995

Mechanism of the burst fracture in the thoracolumbar spine. The effect of loading rate.

STUDY DESIGN: Calf lumbar spine motion segments were randomly assigned to two groups. After insertion of a transducer capable of measuring transient occlusion of the spinal canal during impact, a low rate axial impact was applied in one group and a high rate load in the other. Post-injury computed tomography scans and peak canal occlusions were measured to determine the effect of rate of load application on occlusion of the spinal canal. OBJECTIVES: This study was designed to determine if for the same direction of impact and total energy delivered, occlusion of the spinal canal postvertebral fracture was related to the rate at which the impact was delivered (time from zero to peak load). SUMMARY OF BACKGROUND DATA: Several reports based on clinical observations have hypothesized that axial burst fractures, which displace bone fragments into the canal, occur because of internal pressurization and explosion of the vertebral body. The extent of bursting of the vertebra may depend on the rate of pressurization of the body, which could be related to the rate at which the load is applied. METHOD: Using calf lumbar spines, a transducer was placed within the spinal canal, after removal of the cord, to measure canal occlusion during impact. One group received axial compressive impacts at a mean loading rate of 400 msec (zero to peak load) using a materials-testing machine. The energy of failure was determined and used to select a drop weight and distance for the high loading rate tests, which would yield equivalent impact energy. The second group received impacts at a loading rate of of 20 msec. The post-injury radiographs and canal occlusion measurements were compared. RESULTS: The same mean energy of impact was used in the fractures for both groups. Post-injury radiographs of the low loading rate group showed compressive fractures with a mean canal occlusion of 6.84%, whereas the high loading rate group had burst fractures with mean canal encroachment of 47.6% (P = 0.0007). CONCLUSIONS: For the same energy and direction of impact, a high impact loading rate produces fractures with significant canal encroachment, whereas minimal encroachment is seen for fractures produced at a low loading rate.

Animals↗
PubMed1995

Ultrastructure of spermiogenesis and spermatozoa of Neopolystoma spratti (Platyhelminthes, Monogenea, Polystomatidae).

Spermiogenesis in Neopolystoma spratti conforms to the basic pattern found in polyopisthocotylean monogeneans and in Trematoda Digenea and Trematoda Aspidogastrea. The zone of differentiation exhibits a complete ring of cortical microtubules, two initially free flagella with prominent striated rootlets and an intercentriolar body between them. Mitochondria and nucleus migrate into a median cytoplasmic process and flagella rotate and fuse with this process. Mitochondria fuse to form a single elongated mitochondrion and the nucleus moves to a distal location. Mature sperm have two incorporated axonemes for most of their length, a single elongate mitochondrion and a nucleus. Peripheral microtubules form an incomplete ring in the most proximal region and a complete ring in the adjacent region containing two axonemes and the mitochondrion. In the principal region (where the nucleus is present) they form an incomplete ring and are interpreted as originating from the dorsal and ventral faces of the median cytoplasmic process. Thus, although there are more microtubules in the principal region than at either end, the situation is essentially the same as that found in polyopisthocotylean monogeneans, digeneans and aspidogastreans, with no addition of extra lateral microtubules.

Animals↗
PubMed1995

Ultrastructure of the buccal complex of Polylabroides australis (Monogenea, Polyopisthocotylea, Microcotylidae).

The two buccal suckers have a largely muscular septum each and, near the pharynx, dorsal swellings ("valve apparatus") extend into the lumen of the suckers. In the posterior parts of the suckers, the tegument forms a "rim" containing much electron-dense material. The walls of the suckers are mainly formed by muscle filaments, and there are several large vacuolated masses containing lipid (?) globules and vacuoles. The most anterior part of the pharynx contains a thick layer of electron-dense material which also lines the pharyngeal wall facing the lumen. Nine types of sensory receptors, all with electron-dense collars, were observed in the tegument near the suckers, in the mouth cavity and its extensions, and in the anterior part of the pharynx. Some are uniciliate, one is biciliate, one multiciliate, and two (including the pharyngeal receptors) are nonciliate. The greatest variety of receptors, including receptor complexes consisting of three receptor types, is found in a posterior ventral extension of the mouth cavity. It is suggested that this extension can be protruded into the suckers, facilitated by numerous muscle filaments in the tissue around it.--Septate suckers, mouth cavity and its extension, valve apparatus and pharynx are likely to form a functional whole, the "buccal complex", used for food intake.

Animals↗
PubMed1995

Re-examination of spermatogenesis of Multicotyle purvisi (Platyhelminthes, Aspidogastrea).

Examination of spermatogenesis in Multicotyle purvisi revealed that the process follows the classical pattern previously described for many parasitic platyhelminths, especially other Aspidogastrea and Digenea. Free flagella (with an intercentriolar body between the basal bodies and with striated flagellar rootlets) and a median cytoplasmic process grow from a zone of differentiation. The flagella then fuse with the process in a proximo-distal direction and nucleus and mitochondrion grow out into the elongating spermatid. Spermatids are pinched off at the base, and rootlets and intercentriolar body remain behind in the residual cytoplasm. It is suggested that the aberrant processes described in an earlier report constitute a pathological condition or a response to stress. Changes in the intercentriolar body during spermiogenesis are documented and for the first time in a platyhelminth it is demonstrated that rootlets and intercentriolar bodies are discarded and left behind in the residual cytoplasm.

Animals↗