Regeneration of Polylepis australis Bitt. in the mountains of central Argentina

Polylepis australis woodlands range from northern to central Argentina. They support a high number of endemisms (both plants and animals) and constitute the main cover type in watersheds contributing to retain soil and catch water. Natural regeneration of P. australis in the Córdoba mountains, Argentina, was studied in two communities dominated by P. australis: shrublands and woodlands. The main objectives of the study were: (1) to characterize shrublands and woodlands in terms of physical (physical and chemical soil properties) and biological (Polylepis’ growth form, fern and moss cover) characteristics; (2) to describe P. australis’ soil seed bank and compare seedling and sapling establishment between both communities. The presence of seedlings as well as saplings was quantified, and soil samples were taken so as to characterize the seed bank.

Results showed significant differences in habitat conditions between shrublands and woodlands. Seedlings’ density was higher in the shrublands, while no differences appeared regarding the sapling numbers. A negative correlation was found between seedling numbers and total community cover as well as mosses and ferns cover. Seed density in the soil bank was higher in the woodlands, but overall seed viability was less than 5%. In the shrublands, the most critical stage of the species regeneration cycle was the transition from seedling to sapling, while in the woodlands the main “filter” occurred during seed germination. The low number of saplings observed in both units suggests a stagnation of P. australis regeneration, which could be translated into an unlikely expansion of the species throughout the Córdoba mountains.     

Differentiation and functional connection of vascular elements in compatible and incompatible pear/quince internode micrografts

Micrografts of internodes excised from in vitro grown pear plants (Pyrus communis L. cv. 'Bosc' (B) and cv. 'Butirra Hardy' (BH)) and quince (Cydonia oblonga Mill. East Malling clone C (EMC)), were cultured aseptically to test the effectiveness of their functional vascular reconnection in relation to incompatibility-compatibility relationships that these genotypes exhibit in the field. The incompatible heterograft (B/EMC) showed a marked delay in internode cohesion compared with the autografts (both B/B and BH/BH) and the compatible heterograft (BH/EMC). Even when fused, the translocation of [14C]-sorbitol from upper to lower internode was lower in B/EMC micrografts than in the other combinations. Epifluorescence studies performed with carboxyfluorescin, a specific phloem probe, indicated that the limited translocation was caused by a delay in the establishment of functional phloem continuity between the two internodes. In the B/EMC combination, new differentiated tracheary elements (TE) in the parenchyma tissue at the graft interface between the two internodes were not detected until 30 days after grafting, whereas in the BH/EMC heterograft and both autografts, new xylem connections appeared to cross the interface 20 days after grafting. Immunohistochemical detection (terminal nick-end labeling assay) of the number of cells undergoing nuclear DNA fragmentation at the graft interface confirmed that the limited and delayed TE differentiation in B/EMC heterografts was associated with a decrease in the activity of programmed cell death processes involved in the differentiation of TE.     

Clinical observations of cattle and buffalos with experimentally induced chronic copper poisoning

The susceptibility of cattle and buffalos to chronic copper poisoning (CCP) was compared by using cattle (n = 10) and buffalo (n = 10) steers distributed into two copper supplemented (n = 6) and two control (n = 4) groups. Supplemented animals received 2 mg copper (Cu)/kg body weight daily for one week, with an additional 2 mg weekly until the end of the experiment (day 105). Three liver biopsies (day 0, 45, and 105) were obtained for mineral analyses; clinical examinations and blood samples were obtained every 15 days. Three supplemented cattle and two buffalos with typical manifestations of CCP died. There were no differences in the frequency of mortality between cattle and buffalos; hepatic copper concentration was higher in cattle than buffalos. These findings suggest that buffalos and cattle might be equally susceptible to CCP. However, buffalos accumulate less liver copper than cattle and have a lower threshold of hepatic Cu accumulation, which leads to clinical manifestation of CCP.     

Differentiation of glycans in equine guttural pouches

The aim of this study was to investigate the carbohydrate composition of mucosubstances in the equine guttural pouches using conventional histochemical tests in conjunction with glycolytic digestion to degrade different classes of glycosoaminoglycans. In the goblet cells, the mucopolysaccharides contained chondroitin sulfate B, heparin, heparan sulfate and sialic acid residues. The acinar cells also expressed these substances (except for heparin), whereas the ductal cells produced chondroitin sulfate B and sialic acid. Neutral sugars were also found in each cell type. The diversity of the glycocomponents found in the auditory tube suggests that they may have important functional roles. Indeed, the glycosoaminoglycans provide a hydrophilic environment that prevents dehydration and desiccation of the guttural membranes during air passage. Additionally, these glycomolecules may be involved in the pathogenesis of some bacterial disease in horses, such as equine strangles.     

Electrochemotherapy for the treatment of squamous cell carcinoma in cats: a preliminary report

Squamous cell carcinomas (SCC) of the skin are commonly described in cats. Reported treatments include surgery, radiation therapy and photodynamic therapy. This preliminary study reports on the management of these lesions combining the local administration of bleomycin (plus hyaluronidase for a more uniform distribution) with permeabilizing biphasic electric pulses. Nine cats with SCC graded T(2)-T(4) were treated over a 5 year period, and each cat received two sessions of electrochemotherapy (ECT) 1 week apart. The side effects of this treatment were minimal and limited to mild erythema of the nose. Seven of the cats (77.7%) had a complete response lasting up to 3 years. ECT seems to be a safe and effective option for the treatment of feline sun-induced squamous cell carcinomas and warrants further investigation.     

An approach for ensuring minimum protected area size in systematic conservation planning

One of the most efficient approaches for designing protected area (PA) networks is to use systematic conservation planning software. A number of software packages are available and all of them include a spatial cost or constraint component in their prioritisation algorithms, which allow the user to determine the level of fragmentation of the final PA system. Many conservation planners want to set minimum PA size thresholds, as small PAs are less viable and more expensive to manage, but this can only be achieved with existing software packages by repeatedly reducing the fragmentation levels of the PA system until every PA meets the threshold. Such an approach is inefficient because it increases the size of every PA, not just the smaller ones. Here we describe MinPatch, a software package developed to overcome this problem by manipulating outputs from the Marxan conservation planning software, so that every PA meets the user-defined size threshold. We then investigate the impacts of this approach with a dataset from the Maputaland Centre of Endemism, and find that using MinPatch to meet the PA thresholds is a much more efficient approach than using Marxan alone. We also show that setting a minimum PA threshold can have important effects on where new PAs are located when compared with Marxan outputs. Based on these results, we recommend that conservation planners use MinPatch whenever they want each PA in a network to meet a minimum size threshold.     

Early detection and treatment of screw loosening in triple pelvic osteotomy

OBJECTIVE: To detect early screw loosening in triple pelvic osteotomy (TPO) and to evaluate the efficacy of retightening using fluoroscopic guidance and minimally invasive surgery to maintain acetabular alignment and achieve bone healing. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Sixteen dogs that had TPO. METHODS: Dogs (16) had TPO (21) by using pre-angled plates secured with 3.5 and 4.0 mm screws, with ischiatic or iliac cerclage, for osteosynthesis. In all but 1 TPO at least 1 screw was inserted into the sacral body (43 screws). The mean radiographic screw length inserted in the sacrum was 10.2 mm, and the mean percent sacral engagement was 22%. Dogs were examined clinically and radiographically immediately postoperatively, and at 10, 30, 60, and 90 days to evaluate screw position. Loose screws were retightened through stab incisions using fluoroscopy to locate the screw. RESULTS: TPO was performed without operative complications. At 10 days, 12 TPOs (57%; 11 dogs) had loose screws primarily located in the cranial aspect of the plate. This represented 20% (25) of the inserted screws. In 5 dogs, screw loosening resulted in medial rotation of the acetabular segment. All loose screws were retightened; 3 screws loosened again in 2 dogs and were detected at 60 days. However, the osteotomies healed with the planned acetabular rotation without further intervention. Screw tightening corrected the acetabular segment displacement. Screws correctly seated at 10 days did not subsequently loosen. Clinical and radiographic outcome was judged excellent in all dogs. CONCLUSION: Loose screws in TPO plates can be identified by 10 days postoperatively and retightened using fluoroscopic guidance to achieve acetabular realignment and healing without need for further surgery. CLINICAL RELEVANCE: Postoperative radiographic evaluation of screw position at 10 days after TPO is recommended to detect loose screws. Retightening loose screws should be considered as an alternative to TPO revision or confinement, especially in immature dogs.     

Are Circular External Fixators Weakened by the use of Hemispheric Washers?

OBJECTIVES: To compare the axial mechanical stability of 3 circular external fixators systems with and without hemispheric washers. STUDY DESIGN: Experimental study. METHODS: The axial stiffness and load necessary to produce 0.5 and 1 mm of displacement of 10 circular external fixator constructs from 3 manufacturers were tested on a materials testing machine. The constructs tested included the Small Bone fixator (SBF; Hofmann S.a.S., Monza, Italy), the IMEX ring fixator (IMEX Inc., Longview, TX), and the Multiplanar C-Fix (MCF; PanVet Distribuzione, Seriate, Italy). Five configurations were tested for each construct: (1) conventional nut fixation, (2) hemispheric washer fixation with connecting rods offset by 0, (3) 1, and (4) 2 holes, and (5) with a ring placed at maximum angulation. RESULTS: The loads resisted at 0.5 and 1 mm of displacement did not differ when frame configurations were compared (P =.25733 and.33769, respectively). The linear stiffness of the following configurations were decreasingly stiff: standard constructs, hemispheric washers with connecting rods perpendicular to rings, hemispheric washers with connecting rods offset by 1 hole, hemispheric washers with connecting rods offset by 2 holes, and ring offset in relation to bone model. The SBF constructs tested were 34% and 41% more rigid than the IMEX and MCF constructs tested despite the larger diameter of the connecting rods for the IMEX frames (6 mm) compared with the SBF frames (5 mm). The IMEX constructs tested were 6% more rigid than the MCF constructs tested. CONCLUSIONS: Adding hemispheric washers and angling connecting rods in relation to rings did not influence the loads resisted at 0.5 and 1 mm displacement but decreased construct stiffness. CLINICAL RELEVANCE: The use of hemispheric washers had minor effects on the biomechanical performance of fixator frames tested in this study when used to angle a ring in relation to connecting rods for circular external fixators.     

Processes of environmental degradation and opportunities for rehabilitation in Adwa,Northern Ethiopia

There are only a few studies of land cover-land use changes which provide an integrated assessment of the biophysical and societal causes and consequences of environmental degradation in Ethiopia. Our objectives were to determine the status of the environmental degradation, analyse and evaluate the relationships among vegetation, geomorphological and socio-economic factors contributing to environmental degradation, and propose opportunities for rehabilitation of these natural resources. Field and other environmental data in northern Ethiopia and those acquired by remote sensing techniques were used to accomplish these objectives. These were integrated with socio-economic data obtained from official sources using a Geographic Information System (GIS).Spatial information such as the percent of land cover-land use types and geomorphological categories, and the percent of each land cover-land use type in the geomorphological categories were calculated using Geographic Information System (GIS). The three most dominant features of the geomorphological categories (93.0%) are scarps and denuded rock slopes, erosion surfaces and badlands, while the three most dominant features in the land cover-land use types (71.3%) are croplands, open woodlands and bushlands. Badlands account for 38.7% of the geomorphological units and 41.8% of the croplands currently occur on badlands. Simple and partial correlation analyses were applied to explore the extent of the interaction between the anthropogenic and the natural system. The anthropogenic system is influenced by elevation, which is positively correlated with human population and livestock densities and area of croplands. The natural system finds its place only on steep slopes as shown by the positive correlation between woodland,slope, high potential erosion, scarps and denudational rock slopes. The study indicates that agriculture in the study area is in a critical environmental situation. A change of paradigm in land-use and development is needed to encourage participation of the landowners and users in the efforts to conserve the vegetation and the soil. This study provides sound options that could be used to rehabilitate the vegetation directly and to alleviate the current pressure on the land and improve human welfare indirectly. Matching the human and livestock densities with the carrying capacity of the land through recruitment of the surplus labour force for a modern economy, resettlement,off-farm employment and intensification of agriculture are t he long and short-term actions that may contribute to the rehabilitation of the degraded areas. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mucor Species in Orchard Soil – Population Dynamics and Pathogenicity on Pear Fruit

Strains of Mucor piriformis were isolated from orchard soils and from packinghouse dump-tank waters. Pathogen propagules were not found in fruit sample washings. M. piriformis was the most prevalent of the Mucor isolates, only one of 67 isolates was a different Mucor sp., possibly M. racemosus. The population of the pathogen propagules fluctuated in an annual cyclic pattern, declining in warm months and increasing after harvest. The viability of sporangiospores was markedly affected by rain. There was a good correlation (r=0.88) between the number of recovered propagules in the soil and the amount of rainfall. M. piriformis isolates caused decay on pear at 0°C after 14 days.