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Biomedical subjects

D S Edwards

Publications and source records attributed to D S Edwards.

At least 19 recordsLinked to original sources
PubMed2004

Vaccination and ill-health in dogs: a lack of temporal association and evidence of equivalence.

Following concerns raised over the safety of canine vaccines, an epidemiological investigation was conducted to evaluate the evidence for a temporal association between vaccination and ill-health in dogs. The owners of a randomly selected population of dogs were sent 9055 postal questionnaires, 4040 of which were returned. No temporal association was found between vaccination and ill-health in dogs after adjusting for potential confounders, such as age. However, reliable inferences from non-significant test results are limited and so equivalence-testing methods were also used to make informative inferences. Results demonstrated that recent vaccination (< 3 months) does not increase signs of ill-health by more than 0.5% and may actually decrease it by as much as 5%. This general approach should be used in all field studies of vaccine safety.

Animals↗
PubMed2001

Towards developing a non-SnCl2 formulation for RP444, a new radiopharmaceutical for thrombus imaging.

There are many factors influencing the yield and radiochemical purity (RCP) of the radiopharmaceutical RP444. These include heating temperature, heating time, pH, the use of a buffering agent and a bulking agent, as well as the component (XV066, tricine, TPPTS, and Na99mTcO4) concentration. Through a series of radiolabeling experiments, we found that a formulation comprised of 20 microg of XV066, 6.5 mg of tricine, 40 mg of mannitol, 5 mg of TPPTS, and 0.1 mg of Pluronic acid dissolved in 1.0 mL of 250 mM succinate buffer (pH 5.0) gives the best RCP for RP444. The formulation can be lyophilized to form a stable crystal "cake". The radiolabeling is achieved by adding 1.5 mL generator eluant (33-133 mCi of Na99mTcO4) to a lyophilized vial and heating the reaction mixture at 100 degrees C for 10 min. Using this formulation, RP444 is prepared consistently in high yield with RCP > or = 90%. Formation of [99mTc]colloid is minimal (< 0.5%).

Chromatography, High Pressure Liquid↗
PubMed2000

A 99Tcm-labelled leukotriene B4 receptor antagonist for scintigraphic detection of infection in rabbits.

In a search for a rapid and accurate imaging agent for scintigraphic detection of infection and inflammation, an LTB4 receptor antagonist, 99Tcm-RP517, which contains the hydrazino nicotinamide moiety, has been developed recently. To study the in vivo behaviour of 99Tcm-RP517, rabbits with Escherichia coli infection were injected intravenously with 99Tcm-RP517. Gamma camera images were obtained and ex vivo bio-distribution was determined at several hours post-injection (p.i.). In a separate set of rabbits the choledochal duct was cannulated to quantitatively monitor the hepatobiliary clearance of the radiopharmaceutical. The receptor binding fraction of the radiolabelled RP517 exceeded 70%. Accumulation of 99Tcm-RP517 in the abscess was visualized as early as 1 h p.i. Due to rapid blood clearance (t1/2 alpha=18+/-0.6 min, t1/2 beta=6.5+/-0.4 h) and high abscess uptake, the abscess-to-muscle ratios increased with time from 7.0+/-2.3 at 1 h p.i. to 44.3+/-4.6 at 20 h p.i. The agent mainly cleared via the hepatobiliary route: 50% of the radiolabel was recovered in the small bowel at 1 h p.i., whereas 85% was found in cecum and sigmoid at 20 h p.i. In conclusion, 99Tcm-RP517 rapidly visualized E. coli abscesses in rabbits. The agent rapidly cleared from the blood, mainly via the hepatobiliary route. High abscess-to-background ratios were achieved. The accumulation in the intestines could limit the applicability of this agent for detecting infectious processes in the abdominal area. The development of a more hydrophilic analogue of 99Tcm-RP517 could improve the clinical applicability of this agent.

Acute Disease↗
PubMed1999

Welfare implications of sheep ear tags.

The damaging effects of ear tags used to identify sheep were studied by examining the ears of sheep after slaughter in three different abattoirs and the ears of sheep on a farm. In total, 1040 ears with tags were examined. There were six types of ear tag: metal 'Ketchum' style loop tags; two-piece rigid plastic tags; 'Allflex' style flexible plastic tags with a male and female part; golf tee-shaped plastic ear tags; one-piece rigid plastic loop tags; and one-piece flexible plastic tags with a flap. The metal loop tags and plastic loop tags caused the most lesions, and the majority of the severe lesions. Ear tags placed near to the tip of the ear appeared to cause more damage. Some of the Ketchum style metal tags and two-piece rigid plastic tags appeared to be relatively new, as if recently fitted. These tags were more often associated with ear lesions, particularly moderate or severe lesions. The Allflex style flexible plastic tags caused the fewest problems, and the golf tee-shaped plastic tags also caused significantly fewer problems than the other tags.

Animal Identification Systems↗
PubMed1999

Determination of farm-level risk factors for abnormalities observed during post-mortem meat inspection of lambs: a feasibility study.

To investigate the feasibility of using information about the health and management of lambs on farms to predict the risk of gross abnormalities at post-mortem meat inspection, 6732 lambs from 30 different farms in Great Britain were followed through to slaughter in 1995/6. The farm-level data were collected during farm visits at the beginning of the study. Routine meat inspection findings for the lambs were obtained from the 10 participating abattoirs. The most common abnormalities found during post-mortem inspection were pneumonia/pleurisy (53% of cohorts), lungworm (40%), abscesses (30%), liver fluke (27%) and nephritis/nephrosis (27%). The farm-level risk factors associated with abnormalities at slaughter varied with the type of lesion. The most significant risk factor was the age of the lambs at slaughter. Lambs slaughtered at an older age were more likely to have an abnormality, especially pneumonia, abscesses and liver fluke. After age, environmental factors appeared to be better predictors of those cohorts that would have lesions at slaughter than health and disease control variables. However, a much larger study would be required to identify a set of farm-level factors that adequately discriminated between lambs with high and low risks of lesion at slaughter. At the end of the study, the farmers were informed of the meat inspection findings for their lambs and a third indicated that they would improve their animal husbandry as a result of the information.

Animals↗
PubMed1997

Meat inspection: an overview of present practices and future trends.

This is a review of meat inspection literature, its history, current concerns and needs for the future. The value and limitations of meat inspection are discussed, along with the possible modifications or changes that are being developed to modernize an increasingly outdated method of safeguarding public health. The potential of on-farm risk assessment of slaughter animals and the practical considerations that need to be overcome are outlined. The needs of the consumer and subsequent challenges to the meat and farming industry are proposed as the driving force behind the changes occurring in veterinary public health. The current risk to consumers, from such microbial pathogens as Salmonella, Escherichia coli O157:H7 and Campylobacter infection, are highlighted.

Animal Husbandry↗
PubMed1997

Technetium-99m-labeled chemotactic peptides in acute infection and sterile inflammation.

UNLABELLED: Chemotactic peptides have been proposed as vehicles to image infection and inflammation. Previous studies have shown high uptake at the site of infection soon after injection, most likely because of specific binding to receptors on locally present leukocytes. To investigate this hypothesis, the in vivo behavior of a synthetic chemotactic peptide was compared to a control peptide of similar molecular weight with low receptor binding affinity. In addition, the potential to target to different infections and sterile inflammation was tested. METHODS: Twenty-four hours after induction of Escherichia coli, Staphylococcus aureus and zymosan abscesses, rabbits were i.v. injected with either 1 mCi of 99mTc-labeled formyl-methionyl-leucyl-phenylalanyl-lysine-hydrazinonicotinamid e (99mTc-fMLFK-HYNIC) or 99mTc-labeled hydrazinonicotinamide-methionyl-leucyl-phenylalanyl-OMe (99mTc-HYNIC-MLFOMe, control peptide). Gamma camera images were obtained at 5 min and 1, 4, 8 and 20 hr postinjection. Biodistribution was determined at 20 hr postinjection. RESULTS: The blood clearances of 99mTc-fMLFK-HYNIC and 99mTc-HYNIC-MLFOMe were similar. With time, 99mTc-fMLFK-HYNIC was retained in the abscess (E. coli), whereas the control agent 99mTc-HYNIC-MLFOMe was cleared from the abscess (0.049 +/- 0.011 versus 0.005 +/- 0.0003% 1D/g at 20 hr postinjection; p < 0.0005). Abscess-to-contralateral muscle ratios of 99mTc-fMLFK-HYNIC rose to 36.8 +/- 4.3 at 20 hr postinjection. E. coli, S. aureus and zymosan abscesses were clearly visualized from 4 hr postinjection onward. Abscess-to-background ratios increased to values varying from 4.4 +/- 0.2 (zymosan) to 7.1 +/- 0.6 (S. aureus) at 20 hr postinjection. The uptake in S. aureus and zymosan abscesses did not differ significantly from the uptake in E. coli abscesses. CONCLUSIONS: fMLFK-HYNIC is retained in both acute infection and sterile inflammation by means of specific receptor binding if sufficient cellular infiltration is present.

Abscess↗
PubMed1996

Welfare implications of identification of cattle by ear tags.

The damage caused by ear tags used for identification was studied by examining the ears of normal beef cattle and cull cows after slaughter, and by comparing the effects of metal and polyurethane ear tags in calves which had been double-tagged in the same ear. Metal tags were associated with more damage to the ears than polyurethane tags, the difference being most marked in the young calves, in which slight changes were found in 36.6 per cent and severe changes in 9.8 per cent of ears. There was a high incidence of blood around the point of insertion of the metal tags at three weeks old, but with the polyurethane tags only one calf showed slight evidence of blood around the point of insertion. In the beef cattle fitted with metal tags, a slight reaction was recorded in 40 per cent, a moderate reaction in 17 per cent and significant changes were found in 12 per cent of ears. By comparison, 16 per cent of ears with polyurethane tags showed only a slight reaction, and 80 per cent of the polyurethane tags were considered to be a good fit, compared with 37 per cent of metal tags. More changes were observed in the ears of the cull cows, with 23.5 per cent of ears with polyurethane tags being free from damage, compared with only 2.9 per cent of ears with metal tags.

Animal Identification Systems↗
PubMed1993

Potential 99mTc radiopharmaceuticals for renal imaging: tris(N-substituted-3-hydroxy-2-methyl-4-pyridinonato)technetium(IV) cations.

A series of monocationic complexes of N-substituted-3-hydroxy-2-methyl-4-pyridinones labeled with technetium(IV)-99m have been evaluated in vivo as potential radiopharmaceuticals. The pyridinones have different substituents at the ring nitrogen atom: ethyl, i-propyl, i-butyl, benzyl, phenyl, p-methoxyphenyl, 3-butoxypropyl and cyclohexyl. Biodistribution studies of the 99mTc complexes have been carried out in rabbits and mice. High kidney uptake and retention of the radionuclide has been shown in rabbits and mice with the cationic complexes of 3-hydroxy-1-(p-methoxyphenyl)-2-methyl-4-pyridinone and 1-(cyclohexyl)-3-hydroxy-2-methyl-4-pyridinone. These 99mTcL3+ compounds appear to be morphologic renal agents.

Animals↗
PubMed1991

Early scintigraphic detection of experimental myocardial infarction in dogs with technetium-99m-glucaric acid.

Recent data have generated some interest in technetium-99m-(99mTc) glucaric acid as an in vivo viability marker. We studied 99mTc-glucaric acid retention in canine models of myocardial ischemia (20-min occlusion of the LAD/40-min reperfusion), acute myocardial infarction (MI) (90-min LAD occlusion/3-hr reperfusion), and chronic MI (90-min occlusion and either 48-hr or 10-day reperfusion). Regional myocardial blood flow was measured by radiolabeled microspheres. No preferential uptake of glucaric acid was observed in ischemic but viable myocardium. The compound showed high affinity for necrotic myocardial tissue for several days following injury. The preferential uptake in infarcted tissue disappeared by 10 days following injury. This study shows that 99mTc-glucaric acid acts exclusively as a marker of necrosis in canine models of MI. Technetium-99m-glucaric acid may have clinical utility in early cardiac imaging of myocardial infarction and in differentiating recent from old injuries.

Animals↗