Developing research in partnership with Aboriginal communities - strategies for improving recruitment and retention.

CONTEXT: Australian Aboriginal communities in urban, rural and remote areas are continuing to suffer high rates of perinatal mortality and morbidity that will impact on the future health of the community. It has been well documented that Aboriginal women have extreme distrust of mainstream pregnancy-related health care and suggested that late entry into antenatal care is as high as 50% in the Aboriginal population. Although medical and midwifery staff have long discussed strategies to improve uptake of antenatal health care for Aboriginal women, researchers in many areas have found the recruitment of Aboriginal people into scientific studies almost impossible. This article seeks to share the strategies that have been developed over a period of time by the authors that have proved useful for recruitment and retention into research. It is anticipated that these strategies would also apply for health practitioners in maintaining their patients for clinical care management. ISSUE: Although each research location (regional, rural and remote) has had to spend time determining what approach is best for meeting the research outcomes, many of these suggestions become applicable to clinicians seeking to develop better connections with Aboriginal patients in their clinics. With the management of ongoing chronic health conditions for Aboriginal people a priority in 'Closing the Gap', a number of these suggestions could easily be implemented by clinicians. Remembering that each community has specific needs that must be addressed, priorities for assistance for that community will be easily identifiable after community consultation (eg transport, or ability to access medical testing). Opportunities for the use of new social media (eg Facebook) as communication tools for researchers and clinicians will have increasing applicability as further software updates are created. LESSONS LEARNT: With open and trusting dialogues between researchers, clinicians and Aboriginal communities, we can go a long way towards understanding the needs of individual communities and working in partnerships to close the gap.

A wind tunnel and field evaluation of various dust suppressants.

A series of experiments was designed to assess the relative efficacy of various dust suppressants to suppress PM10 emissions from nepheline syenite tailings. The experiments were conducted in the Trent University Environmental Wind Tunnel, Peterborough, Ontario, and on the tailings ponds at a mine near Havelock, Ontario. Treated surfaces were subjected to particle-free airflow, abrasion with blown sand particles, and particle-free airflow after physical disturbance. Emission rates in the wind tunnel tests were calculated from dust concentration measurements obtained in vertical profile with DustTrak™ II aerosol monitors (model 8530); rates in the field were measured using a Portable In-Situ Wind Erosion Laboratory (PI-SWERL). In the particle-free wind tunnel tests, three of the surface treatments performed well, and PM10 emission scaled inversely with crust strength. Light bombardment of each surface by saltating sand grains increased PM10 emission rates by two orders of magnitude. All treated surfaces emitted significantly more PM10 after physical disturbance. In the field study, plots treated with a commercial dust suppressant were found to release more PM10 than either the control or irrigated plots, although it should be noted that the emission rates were similar in magnitude. As in the wind tunnel experiments, all of the field plots became significantly more emissive after physical disturbance. The field results suggest that the site conditions, inclusive of the potential for dust advection and resuspension, must be taken into account when considering the use of a commercial dust suppressant. Implications: Fugitive dust (PM10) emissions from mining and industrial operations worldwide present significant environmental and human health risks, leaving mine operators challenged to find reliable, durable, and cost-effective mitigation options. Commercial dust suppressants boast unique chemical compositions and commensurate particle binding capabilities, although few side-by-side comparisons exist in the literature. The efficacy of four commercial products to suppress PM10 emissions from mine tailings, before and after physical disturbance, was assessed using robust field and wind tunnel experiments. All surfaces emitted significantly more PM10 after physical disturbance but with considerable variability amongst products. Possible reasons for the differences in relative performance are explored.

Usefulness of pathological examinations of the central nervous system for monitoring and controlling perinatal lamb mortality.

Correct diagnosis of cause of death is necessary to suggest the most effective management interventions to reduce perinatal lamb mortality. Haemorrhage on the surface of the brain has been used as a field diagnostic tool to allocate lambs to a cause of death category, but the usefulness of this method was unclear. This study aimed to evaluate whether gross pathology was related to neuronal death and whether haemorrhage of the central nervous system (CNS) was distinct between differing causes of death, enabling indicators to be used in field diagnoses. Lambs dying from natural causes (n = 64) and from euthanasia (n = 7) underwent postmortem examination, then the brain and spinal cord were extracted and examined histologically. Histological changes consistent with neuronal death were not detected in any lamb. Haemorrhage of the meninges and/or parenchyma of the CNS occurred in all lambs. The age of the haemorrhage indicated that it occurred near the time of death in most lambs. Dilation of blood vessels varied in severity but appeared to be unrelated to causal diagnosis, severity of subcutaneous oedema, breathing or milk status. Moderate or severe dilation of blood vessels and haemorrhage of the CNS did not occur in all lambs with alternative clear indicators of dystocia and occurred in all death classifications, so it could not be used as diagnostic indicators for classification of cause of death. Dilation and haemorrhage were unrelated to neuronal damage and may have been artefactual. In conclusion, haemorrhage of the CNS was not indicative of neuronal damage and could not be used to distinguish between lambs with clear indicators of differing causes of death, so it is not recommended as a field diagnostic tool.

Acute renal failure associated with Amaranthus species ingestion by lambs.

CASE REPORT: This report documents an outbreak of acute renal failure in a flock of 9-month-old White Suffolk-cross ewe lambs. The mortality rate was moderate but the morbidity was high. The lambs had grazed a wheat stubble paddock in which there were several weed species, including Amaranthus spp. CLINICAL SIGNIFICANCE: Renal failure in livestock has been reported internationally following the ingestion of Amaranthus spp. and although it has previously been suspected in Australia no cases have been documented. It is important for Australian veterinarians and farmers to realise the toxic potential of this group of plants.

Survival after neonatal myocardial infarction.

These are case reports of two children with structurally normal hearts and with normal coronary arteries, who survived myocardial infarction in the early neonatal period. They are only the third and fourth reported survivors of neonatal myocardial infarction and the first in which hypercholesterolemia is postulated to have played an important role. The most likely cause of the myocardial infarction was thrombosis or thromboembolism. Changes in hemostatic function associated with hypercholesterolemia may be relevant.

Desensitization of superfused isolated ovine anterior pituitary cells to human corticotropin-releasing factor.

Abstract We have employed an in vitro system to study the time-course of beta-endorphin (beta-EP) immunoreactivity release from anterior pituitary cells stimulated with corticotropin-releasing factor (CRF) and whether exposure to CRF desensitizes the cells to subsequent stimulation. Ovine anterior pituitaries were enzymatically disrupted into single cells, mixed with Siegel P2 and superfused in mini-columns with carbogen-gassed medium at 37 degrees C. Superfusate fractions were collected at 5-min intervals and beta-EP immunoreactivity in the eluate was measured by radioimmunoassay. Peaks of beta-EP release that rose significantly above baseline noise were detected using the PULSAR algorithm. Unstimulated cell columns did not display any spontaneous peaks of beta-EP discharge detectable by PULSAR whereas peaks were identified in the output of columns exposed to 1 nM CRF for 100 min. beta-EP release increased after 10 min of stimulation and maximum stimulated output was achieved after 20 min of continuous CRF exposure. Between 20 and 60 min of CRF stimulation the rate of beta-EP release declined progressively but stabilized in the last 40 min of the exposure at a level significantly above controls for baseline secretion. Peak duration did not depend on the inclusion of calcium in the superfusion medium while peak amplitude and area were significantly reduced when cells were denied extracellular calcium. Following a 100-min exposure to 1 nM CRF, pituitary cell columns were given a 30-min rest period then restimulated with either 1 nM CRF or 50 mM KCI for 20 min. The columns given prior exposure to CRF did not mount a response (detectable by PULSAR) to a subsequent dose of 1 nM CRF whereas PULSAR detected a clear response in all members of a control group that had not received prior CRF challenge. Both CRF exposed and control columns responded to 50 mM KCI although the response was significantly attenuated in the cells that had received prior CRF treatment. These results indicate that unstimulated superfused isolated ovine anterior pituitary cells do not possess an inherent rhythmicity of beta-EP release that can be detected by the PULSAR algorithm while treatment of the cells with CRF results in detectable discharge. The rapid response of beta-EP discharge to CRF treatment suggests the presence of intracellular beta-EP stores available for rapid mobilization. Continuous exposure to 1 nM CRF can tonically amplify corticotrope output for the duration of its presence in the environment of the corticotrope, but the maximum rate of release cannot be maintained. An inrush of extracellular calcium is not essential for the corticotrope to mount a detectable response to continuous CRF exposure but the release of a maximum amount of beta-EP relies on calcium entry. Long-term treatment with CRF prevents the corticotrope releasing a detectable peak of beta-EP on subsequent CRF stimulation and therefore CRF exposure leaves a lasting impression on the physiological machinery of the corticotrope. The attenuation of responsiveness to 50 mM KCI after long-term CRF treatment indicates that depletion of beta-EP stores may play a part in corticotrope desensitization although a reduction in CRF receptor number and an alteration in the intracellular mechanisms controlling beta-EP release may also be a factor.

Variation of radiation sensitivity of Friend erythroleukemia cells cultured in the presence of the differentiation inducer DMSO.

Differentiation of Friend erythroleukemia cells (FELC) was induced with 1.5% dimethyl sulfoxide (DMSO) in the culture medium. Cell growth, erythroid differentiation, and radiosensitivity of the proliferative capacity of the cells were measured and compared to a noninduced control culture of identical age. Induced cells first appeared on Day 2 after DMSO addition, and increased to a maximum of 80 to 90% of the cell population on Day 5, whereas in the control culture, induction was less than 2% of the cells. Radiosensitivity of the cells in the induced culture, relative to that of cells in the control culture, showed an age-dependent variation. On Days 1 and 2 after DMSO addition, the cells in the induced culture were more radiosensitive than those in the control culture. At later times this relationship was reversed, and between Days 3 and 5 the clonable cells in the induced culture were less radiosensitive than those in the control culture. These results suggest that the metabolic events associated with commitment of FELC to differentiate affect their ability to cope with the radiation-induced lesions underlying the loss of division capacity.

Different parameters control motion perception above and below a critical density.

The maximum displacement for the detection of apparent motion (Dmax) is measured using stimuli made up of Gabor function micro-patterns randomly distributed across the stimulus field. Previous studies using high densities of micro-patterns have demonstrated Dmax to be dependent on the spatial frequency content of the stimulus and not the size of the stimulus elements. Here we report that Dmax increases suddenly when the number of micro-patterns in the visual field is reduced beyond some critical point. The number of micro-patterns at which the transition in Dmax occurs is found to be inversely proportional to the width of the micro-patterns along the axis of motion. Beyond this transition, for low density stimuli, Dmax is found to be dependent on both the number and size of micro-patterns in the stimulus field. These results are suggestive of the operation of different motion mechanisms under conditions of low vs high micro-pattern density.

Dependence on stimulus onset asynchrony in apparent motion: evidence for two mechanisms.

The detection of the direction of motion was measured as a function of the spatial and temporal offset for a kinematogram stimulus presented in two-frame apparent motion. The stimulus was made up of Gabor function micro-patterns randomly distributed across the stimulus field. We show that for short stimulus onset asynchronies (SOA) performance can be predicted from the spatio-temporal Fourier power spectrum of the stimulus, whereas for long SOAs the pattern of performance is qualitatively different from such a prediction. The dependence of motion perception on SOA exhibits an abrupt change from one mode of behaviour to the other. These findings are suggestive of the operation of distinct mechanisms, one "quasi-linear" and one "nonlinear", which can be separated by temporal parameters.

The optimal displacement for the detection of motion.

The optimal spatial displacement for the detection of motion by the human visual system was investigated using spatially narrow band stimuli. Direction discrimination was used for abruptly displaced stimuli. An optimal spatial displacement was found for the detection of motion and this bore a characteristic relationship to the spatial wavelength of the stimuli in motion; it was equivalent to 1/6 of the spatial wavelength of the stimulus for low contrast stimuli and 1/5 of the spatial wavelength for higher contrast stimuli. This finding, which in turn suggests that the spatial subunits of motion detectors may be separated by less than 1/4 spatial wavelength, receives some support from other psychophysical and neurophysiological studies.

Luminance contrast and motion detection.

Direction discrimination was used to measure the minimum and maximum displacement for the detection of motion (Dmin and Dmax) for abruptly displaced sinewave gratings. This was measured for a range of contrast levels from 2 to 32 times the detection threshold for a range of spatially narrow band stimuli. Performance for Dmin (but not Dmax) was found to deteriorate with an increase in contrast, with the most sensitive values for Dmin obtained at contrast levels of 4-8 times detection threshold. This dependence on luminance contrast is thought to be due to the physiology of the visual system, rather than the physics of the stimulus.

Motion detection is dependent on spatial frequency not size.

The maximum displacement for the detection of apparent motion is measured using stimuli made up of micro-patterns randomly distributed across the stimulus field. The micro-patterns were Gabor functions or half-wave rectified Gabor functions. Dmax is shown to be dependent of the spatial frequency content of the stimulus, and to be largely independent of the size of the stimulus elements or the number of them in the stimulus field (within limits). Evidence is shown for Dmax to be considered a measure of motion detection that reveals properties of low level underlying motion mechanisms.

Absence of smooth motion perception in color vision.

We have tested the behavioral evidence for a separation of the processing of color contrast from motion in the human visual system. Two different aspects of motion perception are examined; the identification of the direction of movement of a chromatic grating and the perception of smooth motion. The results show that color vision is at no great disadvantage in the identification of direction of movement, since this can be done at color contrasts quite close to detection threshold over a wide range of spatial and temporal frequencies. However, we find that subjects can identify direction without having the genuine perception of smooth motion. Smooth motion perception is revealed to be highly impaired since it is detected only at very high color contrasts and over a narrow range of spatial temporal conditions.

Optimal spatial displacement for direction selectivity in cat visual cortex neurons.

Responses of single neurons in cat visual cortex were measured in response to sinewave grating stimuli. Firstly, a neuron's spatial frequency tuning was determined, and subsequent stimuli were set at the optimal spatial frequency for that neuron. Then a "jumping grating" stimulus was used: a sinewave grating subjected to a series of abrupt spatial displacements, while remaining stationary for a fixed exposure time between displacements. The amount of direction selectivity elicited by this stimulus was measured as a function of the amount of spatial displacement. Visual cortex neurons generally showed an optimal spatial displacement, corresponding to somewhat less than one quarter of a spatial period of the neuron's optimal spatial frequency (close to, but systematically less than, "quadrature phase"). In a majority of neurons tested, this optimal displacement was not affected by increasing the exposure time between displacements, indicating that the measurements were not a simple consequence of temporal frequency tuning. These results closely parallel recent human psychophysical data obtained from measurements of motion aftereffect or direction discrimination elicited by jumping grating stimuli.

Spatial frequency selective mechanisms underlying the motion aftereffect.

The motion aftereffect (MAE) was used to study the spatial frequency selectivity of suprathreshold motion perception. Observers were adapted to drifting sine-wave gratings confined to a retinal eccentricity of approx. 4 deg. The magnitude of the subsequent MAE was measured while viewing a stationary sine-wave grating test surface of one of a number of spatial frequencies. The largest MAE was found when the spatial frequency of the test stimulus was the same as that of the adapting stimulus. This phenomenon held for spatial frequencies between 0.5 and 4 c/deg, and was robust with changes in contrast of either adapting or test gratings. However, at an adapting spatial frequency of 0.25 c/deg, the peak MAE was observed at 0.5 c/deg. Control experiments indicated that this peak shift was not the result of the reduced number of cycles in the stimulus, nor the temporal frequency. There was no measurable MAE at spatial frequencies lower than 0.25 c/deg. These results suggest the existence of a "lowest adaptable channel" for the motion aftereffect.

A nonlinear chromatic motion mechanism.

Previous research has demonstrated two categorically distinct mechanisms mediating apparent motion of kinematograms composed of eccentricity-confined, randomly placed Gabor micropatterns: a quasi-linear mechanism operating for high micropattern densities and short time separations, and a nonlinear mechanism operating at low micropattern densities or longer time separations. Here we compare the performance of these two mechanisms using color (isoluminant) and luminance-defined stimuli. When these stimuli are defined only by their color contrast, the response of the quasi-linear mechanism is severely impaired, while the nonlinear mechanism remains fully operative. This result further strengthens the dichotomy between the two kinds of motion perception, and suggests that when color vision supports motion perception it does so primarily, or perhaps entirely, via a nonlinear mechanism.

Rapid segmentation of one-dimensional noise textures across borders.

We investigated the segmentation of texture pairs that were samples of one-dimensional binary visual noise. The stimulus consisted of an array of 5 x 8 squares separated by two-dimensional noise borders of varying width. The squares were filled with vertical black or white stripes of random width. The task was to detect the presence of a target square which differed from the squares above and below in one of three possible ways: the target pattern was either a contrast inverted copy or a horizontal translation of the pattern in the vertically adjacent squares, or else an independent realization of the noise. The binary noise in the textures was sequentially high-pass filtered to preclude the use of coarse-scale receptive fields and minimize the presence of sparse, extended "features". The target could be detected reliably within 100 msec even when the border width was larger than the maximal stripe width. The border width at threshold saturated for longer presentation times. Our results show that the microstructure of the patterns, i.e. information on the scale of the linewidth in the patterns, is not used directly, even though it contains most of the signal energy and is objectively the most reliable cue to the segmentation.

Directional motion sensitivity under transparent motion conditions.

We measured directional sensitivity to a foreground pattern while an orthogonally directed background pattern was present under transparent motion conditions. For both foreground and background pattern, the speed was varied between 0.5 and 28 deg sec-1. A multi-step paradigm was employed which results in a better estimation of the suppressive or facilitatory effects than previously applied single-step methods (e.g. measuring Dmax or Dmin). Moreover, our method gives insight into the interactions for a wide range of speed and not just the extreme motion thresholds (the D-values). We found that high background speeds have an inhibitory effect on the detection of a range of high foreground speeds and low background speeds have an inhibitory effect on a range of low foreground speeds. Intermediate background pattern speeds inhibit the detection of both low and high foreground pattern speeds and do so in a systemic manner.

Zoladex treatment of symptomatic prostatic carcinoma.

The depot LH-RH agonist Zoladex was used to treat 38 patients with previously untreated symptomatic stage D2 prostate carcinoma. Side effects were minimal and patient acceptability excellent, although temporary tumor flare occurred in 11% of patients. Eighty-four percent experienced subjective improvement and 87% had objective evidence of initial disease stabilization or remission lasting 3 months. Serum levels of gonadotrophin and free testosterone as well as androgens of adrenal origin fell significantly with treatment. Long-term survival to date appears at least as good as that described for conventional endocrine therapy.

Transurethral needle ablation of the prostate: outcome at 1 year.

BACKGROUND: Urologists continue to search for alternatives to transurethral prostatectomy that carry a lower potential for complications. PATIENTS AND METHODS: Twenty-five patients on the public waiting list for transurethral resection of the prostate, all spontaneously voiding, underwent transurethral needle ablation of the prostate (TUNA). Eight patients had a simultaneous bladder neck incision (BNI). Follow-up with International Prostate Symptom Scores and flow rate measurement was performed at 6 weeks, 7 months, and 1 year. RESULTS: A statistically significant increase in flow rate and fall in symptom scores occurred out to 1 year after TUNA. Despite this result, six patients (24%) were not satisfied with their outcome and underwent a second endoscopic operation. CONCLUSION: In our hands, TUNA produced an unsatisfactory clinical result.