Hot spots, indicator taxa, complementarity and optimal networks of taiga.

If hot spots for different taxa coincide, priority-setting surveys in a region could be carried out more cheaply by focusing on indicator taxa. Several previous studies show that hot spots of different taxa rarely coincide. However, in tropical areas indicator taxa may be used in selecting complementary networks to represent biodiversity as a whole. We studied beetles (Coleoptera), Heteroptera, polypores or bracket fungi (Polyporaceae) and vascular plants of old growth boreal taiga forests. Optimal networks for Heteroptera maximized the high overall species richness of beetles and vascular plants, but these networks were least favourable options for polypores. Polypores are an important group indicating the conservation value of old growth taiga forests. Random selection provided a better option. Thus, certain groups may function as good indicators for maximizing the overall species richness of some taxonomic groups, but all taxa should be examined separately.

A mechanical apparatus with microprocessor controlled stress profile for cyclic compression of cultured articular cartilage explants.

An apparatus was designed for mechanical compression of cultured articular cartilage explants with acylindrical plain-ended loading head (diameter 2-5 mm) driven by a stepping motor. A load cell under the culture dish was applied for feedback regulation utilizing a microprocessor-based control unit. The operating programs allowed either continuous or cyclic loading, the latter with adjustable loading/resting ratio. The improvements in the present design compared with previously described apparatuses for similar purposes include: (1) the accurately controlled compression by a load cell and a rapid feedback circuit; (2) the wide range of selectable stresses (25 kPa-12.5 MPa) with both continuous and cyclic loading modes; (3) the ability to handle cycles as short as 1 s with 15 ms peak loading phase. Using a 4 s cycle and 0.5 MPa load for 1.5 h resulted in a significantly enhanced incorporation of radiosulphate in cultured bovine articular cartilage explants, suggesting a stimulation of proteoglycan synthesis. Light and scanning electron microscopic examinations revealed a slight depression and superficial alterations in cartilage structure at the impact site following high pressures. We expect that this apparatus will help in revealing how articular cartilage tissue and chondrocytes respond to external mechanical stimuli.

Comparison of dextranomer and streptokinase-streptodornase in the treatment of venous leg ulcers and other infected wounds.

The clinical efficacy of dextranomer (Debrisan) and streptokinase-streptodornase (Varidase) was compared in a controlled randomized in-patient study. There were two patient groups: Group A consisting of 28 patients with a total of 31 venous leg ulcers and Group B consisting of 56 patients with other infected wounds (posttraumatic and postoperative wounds, amputation stumps, burn wounds, arteriosclerotic ulcers, decubital ulcers, ulcers due to bone disease, rheumatic ulcers, ulcers due to erysipelas and wounds of mixed aetiology). Both agents have a good cleansing effect as well as a good effect on infection and wet necrosis. Dextranomer stimulates the formation of granulation tissue faster than streptokinase-streptodornase.