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Summary:  Microsurgical approaches for the treatment of pathology located in the ventral thoracic spine using video-assisted thoracic surgery (VATS) allow neurosurgeons to access the disc spaces, vertebral bodies, paravertebral soft tissues, spinal cord, spinal nerves, and sympathetic chain with minimally invasive surgery. This has been associated with substantial clinical benefits including reduced postoperative pain, lower complication rates and shorter recovery times when compared with standard thoracotomy techniques. This article describes the experience at our institution with VATS for discectomy (20 cases), corpectomy and spinal reconstruction (8 cases), thoracic sympathectomy (3 cases), and nerve sheath tumor removal (1 case). The technique can be mastered but requires surgeons to learn the new psychomotor skills needed to perform endoscopic spine surgery. The learning curve is steep. Special training in instructional seminars, surgical skill laboratories, and clinical preceptorships is needed before this surgical approach can be used clinically to treat spinal pathology. VATS has significant advantages compared to standard thoracotomy, including reduced incisional pain and avoidance of the postthoracotomy pain syndrome. If intercostal neuralgia develops postoperatively, it is milder and usually transient compared to the pain associated with standard thoracotomy. Better cosmetic outcomes, earlier mobilization, and faster recovery are added benefits. The surgical techniques are relatively new for neurosurgeons and require dedicated practice to master them. Once the surgical skills are perfected, VATS is feasible for spinal pathology and can be performed safely and effectively.

Summary:  The authors report three patients (two males and one female) with herniated thoracic discs whose symptoms mimicked cardiac disease (severe intense stabbing pain beginning in the back and radiating to the lateral wall of the chest). They were evaluated for cardiac disease and angina, but the workup of the heart was negative. Magnetic resonance imaging and computed tomography myelography revealed the herniated thoracic discs. All patients underwent video-assisted endoscopic thoracic discectomy and recovered completely.

The diets of six species of arid zone dasyurid marsupials were investigated at study areas in Queensland and Western Australia. At least 11 orders of insects were taken, as well as spiders, scorpions and centipedes. Beetles and spiders were taken more frequently than expected along foraging trails, whereas ants were avoided; there was no selectivity for other taxa. All species ate small prey (< 2·5 mm long) less frequently than expected. Four of the five species of smaller dasyurids ( 13 g) showed some preference for prey 5·0-7·4 mm long, whereas the largest species, Dasycercus cristicauda (65 g), preferred prey >7·5 mm in length. Dasycercus cristicauda was also the only dasyurid regularly to include large, hard beetles in its diet. Beetles with hard cuticles were not eaten by the small dasyurids, although the three smallest species foraged in areas where hard prey were seldom encountered. Dasyurid marsupials are conspicuously successful inhabitants of the arid zone of Australia; most species are wholly insectivorous. Dietary generalism should be advantageous in arid zone dasyurids by permitting continuous exploitation of a temporally and spatially unpredictable food resource. Copyright 1993, 1999 Academic Press

This study used ecological criteria to evaluate systematically the conservation status of all mammals, birds, reptiles and frogs in New South Wales. The outcome was an official schedule of endangered fauna as defined under the New South Wales National Parks and Wildlife Act 1974 as amended by the Endangered Fauna (Interim Protection) Act 1991. The work was modelled on the study by Millsap et al. (1990) which scored a range of biological variables and used expert opinion to determine priorities for conservation. The listing was undertaken by a statutory Scientific Committee and the results provided the first baseline status list for all species in New South Wales. Of the 883 faunal species (including 10 Lord Howe Island subspecies) identified in the state, 233 (26%) were recognized as endangered. Of these, 40 are considered to be extinct in New South Wales. Mammals constituted the worst affected group, with 77 (59%) of the 130 species recorded as endangered, of which 27 species are recorded as extinct in the state. The assessment of the New South Wales fauna also found that adequate ecological information exists for only 6% of the state's species. The outcome of this study not only provided the first official list of the endangered fauna of New South Wales and explained the methods and reasons for listing or excluding each species, but also furnished new material, ideas and directions for programmes to conserve the state's fauna.

This study investigates the mechanisms of competition between congeneric pairs of insectivorous mammals in two communities in Australia and England. Direct field observations showed that physical interactions between species do not occur, whereas conspecific encounters are frequent. In field enclosures the smaller, subordinate species in each community (Antechinus stuartii: Marsupialia: Sorex minutus: Eutheria) remained alert in the presence of the dominant species (A. swainsonii, S. araneus), and moved quickly away when the latter approached. The rate of prey capture by subordinate individuals also increased immediately after removal of the dominants. Hourly removals of some individuals of the dominant species in each community over 24 h produced hourly increases in the numbers of subordinate individuals that were captured. The rapidity of these responses suggests strongly that the dominant insectivores in each community interfered with the resource use of the subordinate species. Biomass of invertebrates increased inconsistently or slowly within 3 months of removal of the dominant insectivores; hence the rapid responses by subordinate individuals in experiments were not due to simple exploitation or tracking of resource levels. The subordinate insectivores probably detected and avoided contact with dominants instantaneously using auditory or olfactory cues; reciprocal avoidance of congeneric odours was demonstrated using odour-scented traps. Insectivorous mammals may usually compete by interference (or encounter competition, sensu Schoener 1983). For dominant species within communities the cost of interference is minimal and the benefit of gaining exclusive access to resource-rich microhabitats is high. Conversely for subordinate species the benefit of temporarily exploiting the same rich microhabitats may exceed the small costs of vigilance and movement to nearby refugia.

An investigation was made of the effects of reducing and enhancing the intensity of competition on a small marsupial, Antechinus stuartii, from a larger and competitively dominant congener, A. swainsonii. Populations of these species were monitored in two study areas (one control, one experimental) in forest near Canberra, Australia, between February and July in 1980 and 1981. In the experimental study area in 1980 I reduced the numbers of A. swainsonii relative to A. stuartii (thus reducing the intensity of interspecific competition), but in 1981 I augmented the numbers of A. swainsonii (thus increasing the intensity of competition). No manipulations were made in the control study area, and the numbers of both species remained similar there in both years. When the intensity of interspecific competition was reduced, the A. stuartii population increased in size. Increases occurred also in individual movements, home range areas, diurnal activity and in the proportion of large terrestrial prey (larvae, Amphipoda) in the diet. An increase in use of structurally complex forest floor habitats also coincided with decreased arboreal activity. In contrast, when the intensity of competition was enhanced, most of these population and resource shifts were reversed. These findings suggest that reduction in the intensity of interspecific competition allows A. stuartii access to terrestrial sources of food favoured by A. swainsonii, whereas enhancement leads to exclusion of A. stuartii from the forest floor. Competition occurs by interference. This may result in fixed per capita competitive effects of A. swainsonii on A. stuartii, and account for the observed changes in a very broad range of population and resource parameters.

This study tests the hypothesis that competition occurs in a community of three species of small mammals (Antechinus stuartii and A. swainsonii, Marsupialia; Rattus fuscipes, Rodentia) in south-eastern Australia. The hypothesis was tested by using a simple model of competition that is based on two premises: I. competition results in a negative numerical or a negative spatial association between species, and II. competition is more intense where the densities of the competing species are relatively high. The model combines both premises and predicts that measures of association between competing species will be more negative where the species exist at high population densities than derived from the model and applied to data gathered in two study areas with contrasting mean animal densities. There was no evidence of numerical association among the species (three tests), but evidence of negative spatial association (three tests our of four). These latter findings were consistent with the predictions of the model. All species preferred the same broad kinds of habitat (macrohabitat), but they segregated into smaller, finer grained patches (microhabitat) when their numbers were relatively high. Such segregation was more evident between the two species of marsupials than between either species of marsupial and the eutherian rat. These findings suggested that competition occurs by interference, and reinforce the idea that an understanding of the behaviour of individuals is important to understanding competition between species.