Acute onset of pulmonary necrotising arteritis in a dog with a left-to-right patent ductus arteriosus

A 12-week-old, clinically normal Chihuahua was referred for investigation for a continuous heart murmur. Cardiac evaluation revealed an anatomically and haemodynamically typical left-to-right shunting patent ductus arteriosus. The continuous wave Doppler measurement of peak ductal jet velocity of 5.6 m/s was suggestive of a normal pulmonary to systemic arterial pressure ratio. The dog returned 16 days later with right heart failure and severe pulmonary hypertension. Marked reduction in left-to-right shunting was demonstrated and the ductal jet velocity had decreased to 2.5 m/s. Immediate ductus ligation, oxygen therapy before and after the operation, and administration of hydralazine failed to reduce pulmonary hypertension, and the dog was euthanased. Histopathological examination of the lung showed pulmonary necrotising arteritis with acute and chronic arterial lesions. Chronic pulmonary vascular changes related to high flow have been associated with altered nitric oxide and endothelin responses. These changes may be responsible for the acute onset of pulmonary hypertension due to relatively minor vascular insults in some human and veterinary patients with left-to-right shunts. The potential for acute progression supports the recommendations for early ductus ligation and the prognostic importance of detecting pulmonary hypertension presurgically in patent ductus arteriosus patients.     

South-west England grassland survey 1983. 2. Trends in cropping pattern, reseeding and sward composition 1970–83

Seventy-eight farms in south-west England, originally visited in 1970–72, were revisited in 1983 in order to identify changes in land use and re-seeding over the c. 12-year period; changes in sward composition were assessed on fifty-nine of these farms. The results were also compared with Ministry of Agriculture, Fisheries and Food (MAFF) Census results and MAFF Seeds Branch data.
The proportion of tillage had declined from 29 to 24%. This was in agreement with census results for the south-western counties, but contrasted with those for England and Wales as a whole, which showed an increase from 38.8 to 41.7% tillage. It is indicative of grass becoming more predominant in south-west England as east England has become more dominated by tillage cropping.
There had also been a decline in the amount of short-term grassland. In 1970–72 17% of the grassland was intended to last from 1 to 4 years; in 1983 the proportion was only 10%. That these intentions were being carried out was confirmed by the fact that in 1983 there was more grassland in each of the age categories 5·8,9·20 and over 20 years. The trend towards older grassland confirms that shown by regional and national census data, and the trend away from short-term swards is in line with deliveries of herbage seed which indicate reduced use of Italian ryegrass (Lolium multiflorum).
Botanical composition had changed appreciably, with the proportion of Lolium perenne having increased in swards of all ages, e.g. from 35 to 51% in swards 5–8 years old and from 17 to 31% in those aged over 20 years. Other sown species, predominantly Dactylis glomerata and Phleum pratense , had declined markedly in swards over 4 years old. The proportions of Agrostis spp., Festuca spp. and Poa trivialis had fallen, but Holcus lanatus had increased slightly. There had been a marked reduction in infestations of perennial broad-leaved weeds, particularly Ranunculus , but also Rumex and Cirsium spp.     

Polymeric nanoparticles as an oral delivery system for biocontrol agents for the brushtail possum (Trichosurus vulpecula)

Abstract

AIM: To investigate polymeric nanoparticles as an oral delivery system for protein biocontrol agents for control of the brushtail possum, Trichosurus vulpecula.

METHODS: Insulin-loaded poly(ethyl 2-cyanoacrylate) (PECA) nanoparticles were prepared using interfacial polymerisation, and characterised for size, zeta potential, and efficiency of encapsulation of insulin. In-vitro release of insulin-loaded PECA nanoparticles was quantified using reverse-phase highpressure liquid chromatography (HPLC). The in-vivo pharmacokinetics of insulin in PECA nanoparticles was investigated following I/V administration, and when injected directly into the caecum alone or in conjunction with the permeation enhancer EDTA. Blood samples were collected at intervals from ?5 to 180 minutes, and the concentration of insulin in plasma was quantified using a radioimmunoassay (RIA) validated for possum plasma.

RESULTS: Poly(ethyl 2-cyanoacrylate) nanoparticles were produced with a uniform particle size of 200–300 nm, and the mean entrapment of insulin was 78%. In-vitro release of insulin from the PECA nanoparticles was controlled, although incomplete, and approximately 30% of the insulin remained entrapped. The bioavailability of insulin when administered in a PECA nanoparticulate formulation injected directly into the caecum was <1%, and was not increased by addition of the permeation enhancer.

CONCLUSIONS: The nanoparticulate formulations investigated as part of this study resulted in low bioavailability of the peptide insulin in the brushtail possum.     

Response of permanent and reseeded grassland to fertilizer nitrogen. 2. Effects on concentrations of Ca, Mg, K, Na, S, P, Mn, Zn, Cu, Co and Mo in herbage at a range of sites

The concentration of mineral elements in herbage from permanent swards of mixed species composition (predominantly Agrostis spp., Holcus lanatus, Festuca rubra, Lolium perenne, Poa spp., etc.) was compared with that from sown perennial ryegrass ( Lolium perenne ) at two fertilizer rates (0 and 300kg N ha⁻¹ year⁻¹, both with P and K) and with L. perennel Trifolium repens (at 0 N with P and K). The investigation was conducted over four years at sixteen contrasting sites in England and Wales. Herbage samples for mineral analysis were taken at first and fourth harvests (May and August) each year from plots under 4-weekly cutting. There was a wide degree of variation between sites, particularly for concentrations of Ca, Mg, Na and all trace elements analysed. Herbage from L. perenne reseeds had significantly higher concentrations of Ca, Mg, Na, Co and S, but K, Mo, Zn, Cu and P were generally lower than in the permanent swards. L. perennel T. repens swards had the highest concentration of major cations, but trace element levels were generally intermediate between those for 0 N permanent and L. perenne swards. Fertilizer N reduced concentrations of Ca, Mn, Mo and S, and increased Mg, Na and Zn, with no consistent effects on K, Co and Cu. Herbage at harvest 4, compared with harvest 1, had higher Ca, Mg, Na, Mn, Zn and S. Permanent and L. perenne swards responded similarly to fertilizer N and between harvest dates. Results are discussed in relation to previous reports of botanical and fertilizer effects on mineral concentrations, and the mineral requirements of livestock. Changes in mineral concentration resulting from reseeding permanent swards are considered unlikely to increase mineral-related livestock disorders, and in many cases could be beneficial, though problems might arise on sites where some elements, e.g. Cu and Mg, are low.