What are the economic prospects of developing aquaculture in Queensland to supply the low price white fillet market? Lessons from the US channel catfish industry

The farming of channel catfish (Ictalurus punctatus) is the largest (by volume and value) and most successful (in terms of market impact) aquaculture industry in the United States of America. Farmed channel catfish is the most consumed (in terms of volume per capita) fish fillet in the U.S. market. Within Australia, it has long been suggested by researchers and industry that silver perch (Bidyanus bidyanus) and possibly other endemic teraponid species possess similar biological attributes for aquaculture as channel catfish and may have the potential to generate a similar industry. The current teraponid industry in Australia, however, shows very little resemblance to the catfish industry, either in production style or market philosophy. A well established budget framework from the literature on U.S. channel catfish farming has been adapted for cost and climate conditions of the Burdekin region, Queensland, Australia. Breakeven prices for the hypothetical teraponid farms were found to be up to 50% higher than those published for catfish farms however were much lower than those reported for silver perch production in Australia using current, endemic styles of production. The breakeven prices for the hypothetical teraponid farms were most sensitive (in order of significance) to feed prices, production rates, interest rates, fingerling prices and electricity prices. At equivalent feed costs the costs of production between the hypothetical catfish farms in the Mississippi, U.S. and the hypothetical teraponid farms in the Burdekin, Australia were remarkably similar. The cost of feeds suitable for teraponid production in Australia are currently around double that of catfish feeds in the U.S. Issues currently hindering the development of a large scale teraponid industry in Australia are discussed.

Optics of the developing fish eye: comparisons of Matthiessen's ratio and the focal length of the lens in the black bream Acanthopagrus butcheri (Sparidae, Teleostei)

Matthiessen's ratio (distance from centre of lens to retina: lens radius) was measured in developing black bream, Acanthopagrus butcheri (Sparidae, Teleostei). The value decreased over the first 10 days post-hatch from 3.6 to 2.3 along the nasal and from four to 2.6 along temporal axis. Coincidentally, there was a decrease in the focal ratio of the lens (focal length:lens radius). Morphologically, the accommodatory retractor lentis muscle appeared to become functional between 10-12 days post-hatch. The results suggest that a higher focal ratio compensates for the relatively high Matthiessen's ratio brought about by constraints of small eye size during early development. Combined with differences in axial length, this provides a means for larval fish to focus images from different distances prior to the ability to accommodate. (C) 1999 Elsevier Science Ltd. All rights reserved.

STD syndrome packets: Improving syndromic management of sexually transmitted diseases in developing countries

Objective: To design, introduce, and evaluate STD syndrome packets containing recommended drugs for each syndrome, four condoms, a partner treatment card, and a patient information leaflet, with the goal of improving sexually transmitted disease (STD) case management. Methods: Packet design evolved around available packaging technology, informed by pilot testing with nurses working in primary care clinics, doctors in private medical practices, and patients with an STD, in Hlabisa, South Africa. Evaluation 1 year later included analysis of distribution records and interviews with 16 nurses and 61 patients. Results: A cheap packet (2 U, S, cents each, excluding contents) compatible with current legislation was designed and introduced to six public sector clinics and as a short pilot to five private medical practices, Four thousand eighty-five packets were distributed to the clinics, equivalent to approximately 115% of the STDs reported over that period. All 16 nurses reported using the packets, but only 63% did so all the time because of occasional supply problems, All believed the packets improved treatment by saving time (75%), improving supply of condoms and partner cards (44%), and making treatment easier (56%), Patients also responded positively, and most said they would buy a packet (up to $5) at a pharmacy (84%) or store (63%) if available. Conclusions: The STD syndrome packets have the potential to improve STD syndromic management by standardizing therapy and improving the supply of condoms, partner cards, and information leaflets. Packets are popular with practitioners and patients, but consistent supply is essential for maximal impact, There may be scope for social marketing of the packets, which could further increase use.

Hypoxia stimulates cerebral blood flow in the estuarine crocodile (Crocodylus porosus)

The effect of N-2 respiration on cerebral blood flow (CBF) velocity on the dorsal surface of cerebellum was examined in the estuarine crocodile, Crocodylus porosus, using epi-illumination microscopy. Twelve minutes of N-2 respiration resulted in a 126% increase in CBF velocity. N-2 respiration had no effect on blood pressure, indicating an underlying cerebral vasodilation. In addition, heart rate increased significantly. Systemic injections of aminophylline and the NO synthase (NOS) inhibitor nitro-L-arginine (L-NA) did not affect the hypoxia induced increase in CBF. We conclude that C. porosus responds to hypoxia with adenosine and nitric oxide (NO) independent cerebral vasodilation, and that this is likely to be a mechanism protecting the brain from energy deficiency during prolonged dives. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.

Injuries and noncommunicable diseases: emerging health problems of children in developing countries

The present article identifies, for children living in developing countries, the major causes of ill-health that are inadequately covered by established health programmes. Injuries and noncommunicable diseases, notably asthma, epilepsy, dental caries, diabetes mellitus and rheumatic heart disease, are growing in significance. In countries where resources are scarce it is to be expected that increasing importance will be attached to the development and implementation of measures against these problems. Their control may benefit from the application of elements of programmes directed against infectious, nutritional and perinatal disorders, which continue to predominate.

International tourists and road safety in Australia: developing a national research and management programme

Motor vehicle crashes are the leading cause of injury death for international tourists. This makes road safety an important issue for tourism authorities. Unfortunately, as it is in other areas of tourist health, the common response from the travel and tourism industry is to remain silent about this problem and to leave any mishaps in the hands of insurers. At the same time, but for different reasons, international tourists are not usually targeted for road safety initiatives by transport authorities. Given that there are considerable 'hidden' costs associated with international tourists and motor vehicle crashes, the topic should be of concern to both tourism and transport groups. This paper examines issues concerned with driving in unfamiliar surroundings for international visitors in Australia, and proposes a national research and management programme to guide policy and planning in the area. (C) 1999 Elsevier Science Ltd. All rights reserved.

Trial-of-antibiotic algorithm for the diagnosis of tuberculosis in a district hospital in a developing country with high HIV prevalence

OBJECTIVE: To evaluate a diagnostic algorithm for pulmonary tuberculosis based on smear microscopy and objective response to trial of antibiotics. SETTING: Adult medical wards, Hlabisa Hospital, South Africa, 1996-1997. METHODS: Adults with chronic chest symptoms and abnormal chest X-ray had sputum examined for Ziehl-Neelsen stained acid-fast bacilli by light microscopy. Those with negative smears were treated with amoxycillin for 5 days and assessed. Those who had not improved were treated with erythromycin for 5 days and reassessed. Response was compared with mycobacterial culture. RESULTS: Of 280 suspects who completed the diagnostic pathway, 160 (57%) had a positive smear, 46 (17%) responded to amoxycillin, 34 (12%) responded to erythromycin and 40 (14%) were treated as smear-negative tuberculosis. The sensitivity (89%) and specificity (84%) of the full algorithm for culture-positive tuberculosis were high. However, 11 patients (positive predictive value [PPV] 95%) were incorrectly diagnosed with tuberculosis, and 24 cases of tuberculosis (negative predictive value [NPV] 70%) were not identified. NPV improved to 75% when anaemia was included as a predictor. Algorithm performance was independent of human immunodeficiency virus status. CONCLUSION: Sputum smear microscopy plus trial of antibiotic algorithm among a selected group of tuberculosis suspects may increase diagnostic accuracy in district hospitals in developing countries.

High HIV incidence and prevalence among young women in rural South Africa: Developing a cohort for intervention trials

Objective: To measure prevalence and model incidence of HIV infection. Setting: 2013 consecutive pregnant women attending public sector antenatal clinics in 1997 in Hlabisa health district, South Africa. Historical seroprevalence data, 1992-1995. Methods: Serum remaining from syphilis testing was tested anonymously for antibodies to HIV to determine seroprevalence. Two models, allowing for differential mortality between HIV-positive and HIV-negative people, were used. The first used serial seroprevalence data to estimate trends in annual incidence. The second, a maximum likelihood model, took account of changing force of infection and age-dependent risk of infection, to estimate age-specific HIV incidence in 1997. Multiple logistic regression provided adjusted odds ratios (OR) for risk factors for prevalent HIV infection. Results: Estimated annual HIV incidence increased from 4% in 1992/1993 to 10% in 1996/1997. In 1997, highest age-specific incidence was 16% among women aged between 20 and 24 years. in 1997, overall prevalence was 26% (95% confidence interval [CI], 24%-28%) and at 34% was highest among women aged between 20 and 24 years. Young age (<30 years; odds ratio [OR], 2.1; p = .001), unmarried status (OR 2.2; p = .001) and living in less remote parts of the district (OR 1.5; p = .002) were associated with HIV prevalence in univariate analysis. Associations were less strong in multivariate analysis. Partner's migration status was not associated with HIV infection. Substantial heterogeneity of HIV prevalence by clinic was observed (range 17%-31%; test for trend, p = .001). Conclusions: This community is experiencing an explosive HIV epidemic. Young, single women in the more developed parts of the district would form an appropriate cohort to test, and benefit from, interventions such as vaginal microbicides and HIV vaccines.

Dynamic spatiotemporal expression patterns of neurocan and phosphacan indicate diverse roles in the developing and adult mouse olfactory system

The chondroitin sulfate proteoglycans neurocan and phosphacan are believed to modulate neurite outgrowth by binding to cell adhesion molecules, tenascin, and the differentiation factors heparin-binding growth-associated molecule and amphoterin. To assess the role of these chondroitin sulfate proteoglycans in the olfactory system, we describe here their expression patterns during both embryonic and postnatal development in the mouse. Immunoreactivity for neurocan was first detected in primary olfactory neurons at embryonic day 11.5 (E11.5). Neurocan was expressed by primary olfactory axons as they extended toward the rostral pole of the telencephalon as well as by their arbors in glomeruli after they contacted the olfactory bulb. The role of neurocan was examined by growing olfactory neurons on an extracellular matrix substrate containing neurocan or on extracellular matrix in the presence of soluble neurocan. In both cases, neurocan strongly promoted neurite outgrowth. These results suggest that neurocan supports the growth of primary olfactory axons through the extracellular matrix as they project to the olfactory bulb during development. Phosphacan, unlike neurocan, was present within the mesenchyme surrounding the E11.5 and E12.5 nasal cavity. This expression decreased at E13.5, concomitant with a transient appearance of phosphacan in nerve fascicles. Within the embryonic olfactory bulb, phosphacan was localised to the external and internal plexiform layers. However, during early postnatal development phosphacan was concentrated in the glomerular layer. These results suggest that phosphacan may play a role in delineating the pathway of growing olfactory axons as well as defining the laminar organization of the bulb. Together, the spatiotemporal expression patterns of neurocan and phosphacan indicate that these chondroitin sulfate proteoglycans have diverse in situ roles, which are dependent on context-specific interactions with extracellular and cell adhesion molecules within the developing olfactory nerve pathway. (C) 2000 Wiley-Liss, Inc.

Identifying rate-limiting nodes in large-scale cortical networks for visuospatial processing: an illustration using fMRI

With the advent of functional neuroimaging techniques, in particular functional magnetic resonance imaging (fMRI), we have gained greater insight into the neural correlates of visuospatial function. However, it may not always be easy to identify the cerebral regions most specifically associated with performance on a given task. One approach is to examine the quantitative relationships between regional activation and behavioral performance measures. In the present study, we investigated the functional neuroanatomy of two different visuospatial processing tasks, judgement of line orientation and mental rotation. Twenty-four normal participants were scanned with fMRI using blocked periodic designs for experimental task presentation. Accuracy and reaction time (RT) to each trial of both activation and baseline conditions in each experiment was recorded. Both experiments activated dorsal and ventral visual cortical areas as well as dorsolateral prefrontal cortex. More regionally specific associations with task performance were identified by estimating the association between (sinusoidal) power of functional response and mean RT to the activation condition; a permutation test based on spatial statistics was used for inference. There was significant behavioral-physiological association in right ventral extrastriate cortex for the line orientation task and in bilateral (predominantly right) superior parietal lobule for the mental rotation task. Comparable associations were not found between power of response and RT to the baseline conditions of the tasks. These data suggest that one region in a neurocognitive network may be most strongly associated with behavioral performance and this may be regarded as the computationally least efficient or rate-limiting node of the network.

Motor imagery in Parkinson's disease: A PET study

We used positron emission tomography (PET) with O-15-labelled water to record patterns of cerebral activation in six patients with Parkinson's disease (PD), studied when clinically off and after turning on as a result of dopaminergic stimulation. They were asked to imagine a Finger opposition movement performed with their right hand. externally paced at a rate of 1 Hz. Trials alternating between motor imagery and rest were measured. A pilot study of three age-matched controls was also performed. We chose the task as a robust method of activating the supplementary motor area (SMA), defects of which have been reported in PD. The PD patients showed normal de-rees of activation of the SMA (proper) when both off and on. Significant activation with imagining movement also occurred in the ipsilateral inferior parietal cortex (both off and when on) and ipsilateral premotor cortex (when off only). The patients showed significantly greater activation of the rostral anterior cingulate and significantly less activation of the left lingual gyrus and precuneus when performing the task on compared with their performance when off. PD patients when imagining movement and off showed less activation of several sites including the right dorsolateral prefrontal cortex (DLPFC) when compared to the controls performing the same task. No significant differences from controls were present when the patients imagined when on. Our results are consistent with other studies showing deficits of pre-SMA function in PD with preserved function of the SMA proper. In addition to the areas of reduced activation (anterior cingulate, DLPFC), there were also sites of activation (ipsilateral premotor and inferior parietal cortex) previously reported as locations of compensatory overactivity for PD patients performing similar tasks. Both failure of activation and compensatory changes a-re likely to contribute to the motor deficit in PD. (C) 2001 Movement Disorder Society.