Crosspin Fixation of Fractures of the Proximal Tibia in Three Foals

Three foals, each less than 1 month of age, were presented with Salter Type II fractures of the proximal tibial physis. Reduction of the fractures was accomplished manually and maintained by crosspin fixation. Fracture healing in two of the foals was uncomplicated. The third foal developed an infection around the implants, which responded to periodic local antiseptic flushing and administration of penicillin and gentamicin. Follow-up information ranging from 11 to 22 months after surgery revealed satisfactory results in two of three foals; premature closure of the proximal tibial physis was found in the other foal, resulting in the development of an angular limb deformity.     

Critical Transport Infrastructure in Urban Areas: Impacts of Traffic Incidents Assessed Using Accessibility‐Based Network Vulnerability Analysis

Incidents (vehicle breakdowns, crashes, roadworks, lane blockages, severe weather, etc.) are believed responsible for about 50 percent of traffic congestion in Australia's major cities, which is a similar situation to that found in cities in many other parts of the developed world. Incident‐based congestion is particularly disruptive because of its random occurrence in space and time, which maximises the operational impacts of the congestion on social and economic activities. This paper discusses a method for assessing critical locations—congestion “hot spots”—in urban road networks, and the development and application of diagnostic tools that will allow urban road system managers to anticipate potential vulnerabilities to incident‐related congestion and take proactive action to avoid congestion rather than react to it. The expected outcomes are then reduced congestion, delays, and pollution; significantly improved performance from the existing urban road system; and reduced pressure to build more roads. The method involves modelling of travel demand, network topology, capacity and road geometry, the identification and assessment of impacts of traffic incidents at specific locations in a road network, and the use of accessibility impact analysis to assess system‐wide effects. Accessibility impact analysis is undertaken using an accessibility framework, which can account for time of day, transport mode and destination choices by individuals, and level of traffic congestion among other factors. A case‐study application to a specific (potential) incident in a real‐world network indicates that the proposed method is feasible and demonstrates its power in identifying not just total impacts but the distribution of those impacts across a region or community. While current approaches to urban road network planning and management tend to be reactive—finding cures for problems as they arise or addressing locations of recurrent congestion or bad incident record—the vulnerability analysis method described in the paper should lend itself to a proactive approach that can anticipate structural weaknesses and vulnerabilities and help to avoid or at least temper potential adverse effects, rather than to react to them afterwards.     

Growth and viability of hatchery-reared Argyrosomus japonicus released into open and semi-closed systems

Abstract  Hatchery-reared Argyrosomus japonicus (Temminck & Schlegel) were released into estuaries of varying habitat between 1996 and 2004, and growth and recruitment to the fishery evaluated. Fish stocked earlier in summer had significantly faster growth rates ( P  < 0.01), and post-stocking mortality ranged from 1.1% to 11.7% within 7 day post-release. Argyrosomus japonicus stocked in the Georges River in 2003 and 2004 yielded fishery independent recapture rates up to 0.2%. For A. japonicus stocked in Smith's Lake in 1997 and 2004, growth rates, timing of recaptures and increases in commercial catches suggested recruitment to the fishery by 18 months. The 1997 stocking led to a 30-fold increase in A. japonicus catch, but stocking was not financially viable, with a cost:benefit ratio of 2.1. Small, shallow coastal lagoons may represent experimental units for refining stocking strategies, but are not optimal for A. japonicus . The potential for density-dependent effects, and complex relationships between growth, habitat and mortality, highlighted the need for a thorough understanding of species – system interactions. Pilot releases can contribute to this understanding, particularly assessment of habitat requirements, and season, site and size-of-release.     

EFFECT OF pH ON PHOSPHATE ADSORPTION AND ISOTOPIC EXCHANGE IN ACID SOILS AT LOW AND HIGH ADDITIONS OF SOLUBLE PHOSPHATE

Measurements of equilibrium phosphate concentrations, adsorbed phosphate and isotopically exchangeable phosphate (E_t) were made on suspensions of acid soils at initial P concentrations ranging from 1–1000 μM and pH values between 4.2 and 6.8. At low P concentrations (1–100 μM), the affinity of the adsorption reaction was greatest at pH 5.2–5.5. This result, which was inconsistent with the ligand-exchange hypothesis of Kingston et al. (1967, 1972, 1974), was interpreted in terms of the formation of basic aluminium phosphates of varying composition that depended on the OH/P ratio in solution. At the highest P concentrations (1000 μM), when the affinity of adsorption was least at pH 5.2–5.5, it appeared that basic calcium phosphates were precipitating at pH values > 5.5. In suspensions containing 1–100 μM P initially, values of E_t did not change consonantly with values of adsorbed P over the pH range 4.8 to 5.5. It is suggested that the E_t values were underestimated due to the presence of labelled complexes in solution which were detected by scintillation counting but not by the analysis for orthophos-phate. Evidence from solution studies (White et al., 1976) suggested that as much as one-third of the phosphate could be complexed with aluminium in solutions between pH 4.7 and 5.4 at P/A1 mole ratios of 0.075 to 7.5. It was apparent that the interpretation of the physical significance of E values in acid soils is complex and requires careful appraisal of the experimental techniques used.     

Adrenocortical and metabolic responses to dobutamine infusion during halothane anaesthesia in ponies

The study investigated whether hypotension in halothane-anaesthetised ponies is the stimulus inducing an endocrine stress response by assessing the effect of maintenance of normotension with a dobutamine infusion. Groups of six ponies were studied. After premedication with acepromazine (0.04 mg/kg) anaesthesia was induced with thiopentone (10 mg/kg) and maintained for 120 min with halothane (group AN). Dobutamine was infused to effect (1.1–4.4 μg/kg/min) to maintain arterial pressure at pre anaesthetic levels. The conscious group (CON) were prepared as for AN and then received only dobutamine infusion 1.0 μg/kg/min for 120 min. Arterial blood pressure, pH, oxygen and carbon dioxide tension, pulse rate, haematocrit, and plasma cortisol, glucose and lactate concentrations were measured before, at 20 min intervals during anaesthesia, and 20 and 120 min after anaesthesia ceased. Blood pressure remained close to control in both groups. The AN group became hypercapnic and acidotic, pulse rate and haematocrit increased, cortisol increased more than twofold and plasma glucose and lactate did not change. All values remained at control in the CON group except for small increases in haematocrit and decreases in pulse rate. Maintenance of normotension during halothane anaesthesia did not blunt the adrenocortical response to anaesthesia nor did the same dose of dobutamine alone increase plasma cortisol. Hypotension appears not to be the sole stimulus to equine adrenocortical activity during halothane anaesthesia.     

Absorption and pharmacokinetics of phenylbutazone in Welsh Mountain ponies

The disposition of phenylbutazone (4.4 mg/kg), administered intravenously to six Welsh Mountain ponies, was described by a two-compartment open model. Pharmacokinetic parameters were not significantly different after morning dosing in comparison with afternoon dosing. When phenylbutazone (4.4 mg/kg) was administered orally to the same ponies, marked variations in time to peak concentrations were produced with different feeding schedules. When access to hay was permitted before and after dosing, the mean time to peak concentration was 13.2 +/- 1.2 h and double peaks in the plasma concentration-time curve were common. Double peaks were also encountered when phenylbutazone was given to ponies deprived of food prior to, and allowed access to hay after, dosing. In this circumstance, mean times to peak concentration were much shorter (3.8 +/- 1.3 h after morning dosing and 5.3 +/- 1.5 h followed afternoon dosing). Absorption was more regular and double peaks were less apparent when food was withheld both before and after dosing. In order to explain these findings, it is tentatively postulated that, whereas some of the administered dose of phenylbutazone may be absorbed quickly, some may become adsorbed on to the feed and subsequently released by fermentative digestion in the large intestine and/or caecum. The consequences of delayed absorption in fed animals for toxicity and clinical efficacy, and for the use of phenylbutazone in equestrian sports, are considered. Delayed absorption in ponies given access to hay was not accompanied by a significant reduction in total absorption. Bioavailability was estimated to be approximately 69% in fed and 78% in unfed ponies. Estimates of bioavailability gave similar values for morning (72%) and afternoon (71%) dosing.     

Serological detection and identification of bacteria from plants by the conjugated Staphylococcus aureus slide agglutination test

A rapid slide agglutination test using polyclonal antisera conjugated to protein A-rich whole-cell Staphylococcus aureus was developed for the detection and identification of bacteria from plants. The specificity and sensitivity of the technique was evaluated in 18 antibody/antigen combinations, representing six bacterial genera ( Erwinia, Lactobacillus, Pseudomonas, Rhizobium, Rhodococcus and Xanthomonas ). For two pathovars of Pseudomonas syringae the specificity of the technique was increased by the use of antisera prepared to somatic extracts.
The advantages of the Staphylococcus aureus agglutination technique include speed, simplicity and the ability to identify organisms directly from infected plant tissues. It was applied to the detection of Pseudomonas syringae pv. phaseolicola and pv. pisi in lesions on bean and pea, respectively, to P. gladioli pv. alliicola and Lactobacillus sp. from rotted onion bulbs and specific strains of Rhizobium phaseoli in bean root nodules.