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Biomedical subjects

R Hockey

Publications and source records attributed to R Hockey.

16 recordsLinked to original sources
PubMed2003

Gastroschisis: can prenatal sonography predict neonatal outcome?

OBJECTIVE: Gastroschisis is associated with significant neonatal morbidity, and occasionally mortality. Previous studies looking at ways to prognosticate this condition by antenatal ultrasound have shown conflicting results. The aim of this study was to evaluate the usefulness of prenatal sonographic parameters to predict neonatal outcome of gastroschisis. METHODS: The charts, photographs, and videotapes of all fetuses with gastroschisis who were assessed during pregnancy at the Mater Mothers' Hospital, Brisbane over an 8.5-year period (Jan 1993-May 2001) were reviewed. Adverse neonatal outcome was defined as death, severe bowel complications (atresia, perforation, necrotic segments), need for multiple bowel operations, or a combination of these. Various sonographic parameters assessed included: gestation at first diagnosis, maximum bowel diameter, maximum bowel wall thickness, presence of other anomalies, evidence of growth restriction, and polyhydramnios. RESULTS: Forty-five patients met the entry criteria during the study period. Six neonates died, 12 had severe bowel complications, and 15 had a combination of the adverse outcomes. Polyhydramnios was most significantly associated with severe bowel complications, with a likelihood ratio of 11.7 (P = 0.001). Other ultrasound parameters were not significantly correlated with neonatal outcome. CONCLUSION: Most standard ultrasound parameters assessed antenatally in fetal gastroschisis were not significantly associated with adverse neonatal outcome, except for polyhydramnios, which was strongly predictive of severe bowel complications in the neonatal period. This information is important both for parents and for health professionals managing pregnancies with fetal gastroschisis.

Adolescent↗
PubMed2001

Childhood poisoning in Queensland: an analysis of presentation and admission rates.

OBJECTIVE: To determine the presentation rates for paediatric poisoning by ingestion and the determinants of hospital admission. METHODOLOGY: Cross-sectional survey using an injury surveillance database from emergency departments in South Brisbane, Mackay and Mt Isa, Queensland, from January 1998 to December 1999. There were 1516 children aged 0-14 years who presented following ingestional poisoning. RESULTS: The presentation rates for poisoning were 690, 40 and 67 per 100000 population aged 0-4, 5-9 and 10-14 years, respectively. The admission rates to hospital for poisoning were 144, 14 and 22 per 100000 population aged 0-4, 5-9 and 10-14 years, respectively. Although presentation rates for poisoning were higher in the rural centres the admission rates were disproportionately high for the 0-4 years age group. The agents most frequently ingested were paracetamol, Dimetapp, rodenticides and essential oils. CONCLUSION: There is a need to design and implement interventions aimed at reducing poison exposures and unnecessary hospital admissions in the 0-4 years age group.

Adolescent↗
PubMed2001

Minimum acceptable standards for digital compression of a fetal ultrasound video-clip.

If the Internet could be used as a method of transmitting ultrasound images taken in the field quickly and effectively, it would bring tertiary consultation to even extremely remote centres. The aim of the study was to evaluate the maximum degree of compression of fetal ultrasound video-recordings that would not compromise signal quality. A digital fetal ultrasound videorecording of 90 s was produced, resulting in a file size of 512 MByte. The file was compressed to 2, 5 and 10 MByte. The recordings were viewed by a panel of four experienced observers who were blinded to the compression ratio used. Using a simple seven-point scoring system, the observers rated the quality of the clip on 17 items. The maximum compression ratio that was considered clinically acceptable was found to be 1:50-1:100. This produced final file sizes of 5-10 MByte, corresponding to a screen size of 320x240 pixels, running at 15 frames/s. This study expands the possibilities for providing tertiary perinatal services to the wider community.

Female↗
PubMed2000

Mutation of a nuclear receptor gene, NR2E3, causes enhanced S cone syndrome, a disorder of retinal cell fate.

Hereditary human retinal degenerative diseases usually affect the mature photoreceptor topography by reducing the number of cells through apoptosis, resulting in loss of visual function. Only one inherited retinal disease, the enhanced S-cone syndrome (ESCS), manifests a gain in function of photoreceptors. ESCS is an autosomal recessive retinopathy in which patients have an increased sensitivity to blue light; perception of blue light is mediated by what is normally the least populous cone photoreceptor subtype, the S (short wavelength, blue) cones. People with ESCS also suffer visual loss, with night blindness occurring from early in life, varying degrees of L (long, red)- and M (middle, green)-cone vision, and retinal degeneration. The altered ratio of S- to L/M-cone photoreceptor sensitivity in ESCS may be due to abnormal cone cell fate determination during retinal development. In 94% of a cohort of ESCS probands we found mutations in NR2E3 (also known as PNR), which encodes a retinal nuclear receptor recently discovered to be a ligand-dependent transcription factor. Expression of NR2E3 was limited to the outer nuclear layer of the human retina. Our results suggest that NR2E3 has a role in determining photoreceptor phenotype during human retinogenesis.

Amino Acid Sequence↗
PubMed1998

[A methodological study in a space flight simulation context].

To study the effects of isolation and confinement on small groups during long space flights, it is habitual to use closed hyperbaric ground chambers. For the first time, the European Space Agency made use of a nautral environment taking advantage of an Antarctic winter-over at the French Dumont d'Urville Station. The main objective of that study ("International Antarctic Psychological Programme"), was to compare different Russian tests used for training cosmonauts to a W. European approach validated during previous winter studies and European ground chamber simulations. Russian techniques appeared to be oriented to a narrow range of phenomena and unsuited to discern the adjustment to stress conditions.

Adaptation, Psychological↗
PubMed1993

Screening for osteoporosis by bone densitometry: a stratified intervention approach.

We have performed computer modelling of the relationship between bone mass, age and hip fracture in a conditional probability model using a national population of 100,000 postmenopausal women aged 50 who have their bone density measured once. The computer model very closely reproduced the actual number of fractures in a Western Australian population. Intervention to bone loss completely in subjects with the lowest bone density (below 1 SD below the mean) would prevent 0.42 of a hip fracture per patient treated if the whole population were treated. Halving the rate of bone loss in the whole population would reduce hip fracture by two-thirds. These data suggest that hormone replacement therapy, which is the most effective therapy for preventing bone loss but which has the most side effects, should be focused on subjects with bone mass below 1 SD below the mean. The remainder of the population could be targeted with a public health campaign based on the lifestyle factors of increased dietary calcium and exercise which have been shown to slow but not stop bone loss.

Bone Density↗
PubMed1993

European isolation and confinement study. Workload and stress: effects on psychosomatic and psychobiological reaction patterns.

Six healthy males, the EMSInauts, were isolated in hyperbaric chambers for a period of 28 days at 5-msw overpressure. During that period they had to carry out meaningful operational and research tasks in addition to monitoring their psychological and physiological reactions. The actual workload was evaluated and compared with the planned workload, and its effects on symptomatology and psychobiology. The perceived workload and its effects on psychosomatic symptomatology and on some biological indices were monitored. Thus it was possible to evaluate how the workload carried during 4 weeks of isolation affected the psychological and biological well-being of the six EMSInauts. The following three types of assessments were performed: 1. Workload assessment: The objective workload was calculated based on the schedule which was revised daily, and the actual load calculated by the commander. A workload questionnaire was administered daily after each working session. 2. Psychosomatic assessment: Morning and evening questionnaires were administered daily. The state of health and of anxiety were also evaluated. 3. Biological indices: Cortisol, testosterone, adrenalin, and noradrenaline were determined once a week. In addition, cardiac activity was monitored every day. The workload assessment showed that on the average the planned workload was accomplished in slightly less than the scheduled time. The workload was not perceived as severe in terms of cognitive, emotional, and physical load. The group rated the support received from each other and from the mission control personnel as average, with minor changes during the isolation period. They gave a high rating to the amount of control they had over their activities. Fatigue and tension were scored in the middle range. The psychosomatic assessment showed that there were few symptoms, and these were mostly of low severity. The most common symptom was general fatigue. Furthermore, minor dizziness, headache and light tremor was in some cases reported. The sleep quality was good, but complaints about poor sleep increased somewhat with the passing of time. Few and mostly minor health problems were experienced during isolation. Only one EMSInaut had to miss one day of work due to a bout of flu. The state of anxiety was below that of the general population throughout the isolation period. The biological indices used showed no evidence of stress from the workload handled during the isolation period. The level of the "stress hormone" cortisol actually decreased during isolation. The adrenalin excretion, which tends to go up during acute stress, remained unchanged during this period. Neither was there any evidence of changes in cardiac activity throughout the isolation period.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Psychological↗
PubMed1992

Review of the benefits of treating hypertension.

The main points covered in this review are as follows: 1. Hypertension is a major determinant of cardiovascular disease (CVD). As such it is a major cause of mortality, potential years of life lost, morbidity and long-term disability. 2. The incidence of CVD is directly related to BP. It is likely that this extends over the full range of BP although some writers believe that a J-curve of risk exists for CHD. 3. The relationship between long-term disability from CVD and BP requires further study. 4. Because of regression dilution bias, the gradient in risk of stroke and CHD with BP has been underestimated in the past. Recent research suggests that the risk of stroke increases at least tenfold and CHD sixfold over a range of usual DBP of 30 mmHg (equivalent to approximately 50 mmHg baseline DBP). 5. The population attributable risk (PAR) of CVD related to general elevation of BP in the population from a mean daily excess of sodium intake of 100 mmol/day is at least 30%. In typical industrialised countries the PAR for stroke and CHD from clinical hypertension is 36% and 22%, respectively. These estimates of PAR provide a guide to the maximum benefit that could result from either restriction of sodium intake in the whole population or ideal management of all persons with hypertension. In practice such targets are unlikely to be realised. 6. Recent analyses of clinical trials of treatment of hypertension suggest that the risk of stroke is reduced at all levels of initial BP to the extent predicted from observational studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMed1991

Peripheral visual changes and spatial attention.

Three experiments are reported investigating the attentional effects of peripheral visual changes. In agreement with previous work, experiment 1 demonstrated facilitatory and inhibitory effects of a peripheral visual change on the latency of peripheral target detection. However, after a few minutes practice the facilitatory effect disappeared entirely. The inhibitory effect, though slightly reduced in later blocks, remained significant. Hence, the two effects are dissociable and not inter-dependent as argued by Maylor (1985). In experiments 2 and 3 the perceptual salience of the peripheral cue was manipulated. With a low energy, barely noticeable cue there was no reduction in either facilitation or inhibition as a function of practice. In contrast, the attentional effects of cues higher in energy tended to diminish with practice. Theoretical implications of these data are discussed.

Adult↗
PubMed1989

Trends in risk factors for vascular disease in Australia.

Data from the National Heart Foundation Risk Factor Prevalence Surveys of 1980 and 1983 were analysed to detect national trends in risk factors for vascular disease in Australia. After statistical adjustment for differences in the demographic characteristics of the two populations of survey participants, our results show trends in smoking and blood pressure that are likely to result in a continuing fall in the incidence of vascular disease. There was a fall in the prevalence of current smoking from 32% to 29% but little change in the average daily consumption of cigarettes by current smokers. The prevalence of previously-undetected hypertension fell significantly from 10% to 7%. A small increase occurred in the proportion of all hypertensive patients who were treated and whose blood pressure was controlled, and a decline of 2.0 mmHg (P less than 0.0001) in mean diastolic blood pressures, but no significant change in mean systolic pressures. Mean total plasma cholesterol levels did not change; average levels of plasma triglycerides fell by 0.11 mmol/L (P less than 0.0001); and mean high-density lipoprotein cholesterol levels increased by 0.03 mol/L (P less than 0.0001). All indices of relative body weight increased between 1980 and 1983; mean body mass index rose by 0.23 with associated rises in the prevalence of obesity and of overweight status. The changes in other factors such as use of added salt, the consumption of alcohol, the level of physical activity and adherence to a special diet, all were in the desirable direction, although minor changes in the survey questionnaire might have served to exaggerate the apparent trends.

Adult↗
PubMed1987

Effects of repetition on the facilitatory and inhibitory components of orienting in visual space.

Three experiments are reported which investigate the possibility of habituation of externally-controlled covert orienting with repetition. A brief event in the visual field (for example, a luminance change) can speed the detection response to a target if it occurs in the same location within approx. 100 msec and can bias temporal order judgments in the absence of eye movements. This early facilitatory component is seen as the result of an externally-controlled covert orienting response, that is, the realignment of attention, but not the eyes, with the location of the initial event. However, after approx. 300 msec, the response to a target appearing in the same location is slower than to one appearing elsewhere (the inhibitory component). Experiment 1 employed a cue-target procedure, the subject's task being to ignore each non-informative cue but to respond as quickly as possible to the onset of each target. Three conditions were investigated which differed according to the number of consecutive cues presented in the same location [1, 5, 30]. Facilitatory and inhibitory components were present in all three, indicating that under these conditions, externally-controlled covert orienting does not habituate with repetition and occurs to non-random as well as random sequences of cues. In addition, there was evidence that the inhibitory component is larger for a response to a target appearing in the same location as the cue and the previous target than in the same location as the cue only. In order to investigate this further, a continuous target-target procedure was used in experiments 2 and 3 (simple and choice reaction time, with 3 and 1 response-stimulus intervals respectively), which demonstrated that inhibition does not build up over successive repetitions of targets appearing in the same location, but actually decreases. The results are discussed in relation to the possible functions of the facilitatory and inhibitory components in maintaining selectivity in visual space.

Arousal↗
PubMed1986

Selective attention and performance with a multidimensional visual display.

Selective attention was studied in four experiments in which stimuli varied in both spatial location and visual form. In Experiment 1 the likely location and likely form of targets were both precued. An advantage was found for cued over uncued forms at both cued and uncued locations. In Experiments 2, 3, and 4, different forms tended to occur at different locations. Regardless of whether a location was cued or uncued, form selective effects were found in accordance with form probability for that location. It was not the case that selective attention simply favored certain locations or certain stimulus forms in preference to others. Rather, selective attention was sensitive to precise combinations of form and location. These results could not be reconciled with mental spotlight notions of spatial selectivity.

Adult↗
PubMed1986

Symptoms and longitudinal changes in lung function in young seasonal grain handlers.

A total of 119 seasonal grain handlers (mean age 23) were assessed before and towards the end (mean work period 18 days) of the 1983 Western Australian grain harvest to determine if respiratory symptoms that occur with exposure to grain dust are associated with changes in ventilatory capacity or non-specific bronchial reactivity to methacholine. Eighteen per cent of subjects had wheeze, breathlessness, or chest tightness and 18% had cough or sputum production at work. Subjects complaining of wheeze, chest tightness, or breathlessness at work had a significantly greater decline in FEV1 than subjects who did not experience these symptoms (p less than 0.05). Symptoms were not associated with changes in bronchial reactivity. In young grain handlers who develop respiratory symptoms on short term exposure to grain dust changes in FEV1 but not in non-specific bronchial reactivity have been demonstrated.

Adolescent↗
PubMed1985

Inhibitory component of externally controlled covert orienting in visual space.

Four experiments are reported that investigate an inhibitory effect associated with externally controlled orienting and first identified by Posner and Cohen (1980, 1984). The effect takes the form of an inability to respond quickly to a stimulus appearing in the same location in the visual periphery as a previous one that produced covert orienting. Several characteristics of the effect are revealed that eliminate possible explanations in terms of response inhibition, masking, and sensory habituation. The inhibitory component of orienting occurs whether or not the first stimulus requires a response (Experiment 1), lasts at least a second (Experiments 1, 2, and 3), affects not only the originally stimulated location but also nearby locations (Experiment 2), is determined by environmental coordinates (Experiment 3), and occurs both in the periphery and at the fovea (Experiment 4). It is concluded that inhibition may act together with an early facilitatory component (Posner & Cohen, 1984) in directing the attention and eye movement systems in order to maintain efficient spatial sampling.

Form Perception↗