Plasma thyroid hormone concentrations in dogs competing in a long-distance sled dog race

Plasma thyroxine (T4), 3,5,3'-triiodothyronine (T3), total protein, and albumin concentrations were measured in 15 dogs both before and after completion, and in an additional 16 dogs before and 24 dogs after completion, of a long-distance sled dog race. The plasma T4 concentration (mean +/- SD) decreased significantly from 18.2 +/- 5.4 nmol/L before to 14.3 +/- 3.5 nmol/L after the race in dogs evaluated at both times and decreased significantly from 21.8 +/- 10.5 nmol/L before to 15.8 +/- 4.9 nmol/L after the race in dogs sampled only before or only after the race. The mean plasma T3 concentrations in dogs measured twice decreased significantly from 1.20 +/- 0.48 nmol/L before to 0.74 +/- 0.42 nmol/L after the race, as well as in dogs measured either before (1.28 +/- 0.36 nmol/L) or after (0.69 +/- 0.28 nmol/L) the race, respectively. Plasma total protein and albumin concentrations decreased significantly after completion of the race. No significant change was noted in 4 control dogs that did not compete in the race and were tested during a similar time period. The plasma concentrations of T4 and T3 were lower than the normal reference range established for this laboratory in 23 and 39%, respectively, of Alaskan sled dogs tested before the race. Plasma thyroid hormone concentrations frequently are below normal in conditioned Alaskan sled dogs and are further reduced after prolonged submaximal exercise.     

Enhancing immunity to nematode parasites in single-bearing Merino ewes through nutrition and genetic selection

The effectiveness of protein supplementation and genetic selection to enhance the resistance of periparturient Merino ewes to infection from gastrointestinal parasites was tested in a replicated grazing experiment. One hundred and twenty ewes from lines selected for increased resistance (R) to Haemonchus contortus or at random (C) were subjected to one of the three supplement groups that provided 0 or 250 g per day cottonseed meal for 5 weeks prior to, or for 6 weeks after the start of lambing. Faecal egg counts (FEC) of R ewes were consistently lower than those of C ewes but both groups exhibited a periparturient rise in FEC. Supplementation during the pre-partum period reduced FEC and increased ewe body weight gain. The benefits of pre-partum supplementation in reducing FEC continued to be apparent up to 10 weeks after supplementation ceased. There was a strong suggestion that the benefits to parasite resistance from protein supplementation were greatest in C ewes. Wool growth rates (15%) and birth weights (5%) were greater for C ewes but differences between the lines for lamb body weight had disappeared by day 97. The greatest benefit to resistance from protein supplementation was observed when ewes were experiencing a loss of maternal body weight. Conversely, no benefits to resistance were observed when ewes had moderate (78-107 g per day) rates of maternal weight gain. These results suggest that increased resistance as a result of protein supplementation is dependent on the prevailing supply and demand for scarce nutrients such as metabolisable protein (MP). Both genetic selection and protein nutrition are effective strategies to enhance host resistance to nematode infection during the periparturient period.     

Immunological relationship between Neospora caninum and Besnoitia besnoiti

Neospora caninum is a coccidian parasite identified as a major cause of abortion in cattle. A combined infection of N. caninum with another taxonomically related parasite of cattle, Besnoitia besnoiti can occur in geographical areas endemic for both species. Both infections are routinely diagnosed serologically, and incorrect diagnosis could occur if immunological cross-reactivity exists between the two parasites. To investigate the possible degree of cross-reactivity, we compared results obtained with two serological techniques, immunofluorescent antibody test (IFA), and Western blot analysis on known positive and negative sera. The test sera were derived from naturally infected cattle and from experimentally infected Mongolian gerbils. In IFA of bovine sera, no cross-reactvity was detected at the commonly used serum dilution cutoffs of 1:200 for N. caninum and 1:256 for B. besnoiti. However, at 1:64 dilution of both cattle and gerbil sera, anti-N. caninum sera reacted with B. besnoiti antigen in some individual samples. Anti-B. besnoiti serum did not react with N. caninum antigen at any dilution. This low level one directional cross-reactivity was confirmed by Western blot analysis. B. besnoiti antigen showed two immunoreactive bands when probed with anti-N. caninum serum, while no bands appeared when N. caninum antigen was probed with B. besnoiti antiserum. Immunization and challenge experiments in the highly susceptible Mongolian gerbil (Meriones unguiculatus) showed essentially no cross-protection between N. caninum and B. besnoiti.     

Photocatalytic degradation of pesticides and bio-molecules in water

Two approaches are suggested for the acceleration of the photocatalytic oxidation of organic contaminants of water: acceleration by oxidants and photo-enhancement by dyes. These processes were examined with several substances: two widely applied herbicides, bromacil (a uracil) and metribuzin (a triazine), and three proteins, studied as models of biocontaminated waters. The effects of oxygen and hydrogen peroxide indicated two different reaction patterns of photo-oxidation of the herbicides. With metribuzin, oxygen had a pronounced effect on the rate of photo-oxidation, while the influence of hydrogen peroxide was quite moderate; with bromacil, oxygen had a limited effect on the rate of photo-oxidation, which however was considerably enhanced by hydrogen peroxide. Acceleration of the photo-catalytic oxidation of colourless refractory contaminants by photo-excited dye was observed. Both UV and visible light were required for the enhanced decomposition. The mechanism of the reaction seems to involve a combination of oxidation by hydroxyl radicals, via the hole-electron semiconductor route, with subsequent oxidation of photo-intermediates by singlet oxygen formed by dye sensitization. The TiO2-photocatalyzed oxidation of proteins (albumin, ovalbumin and gamma-globulin) showed the susceptibility of proteins to photocleavage and of the amino acids to photocatalytic degradation. Tyrosine was the most sensitive, while the degradation of the aliphatic amino acids Gly and Asp was slow.     

Hippeastrum mosaic virus and another filamentous virus in Eucharis grandiflora

Two viruses were found in mosaic-diseased plants ofEucharis grandiflora in a glasshouse of the laboratory. One virus with a normal particle length of 733 nm caused local lesions onHyoscyamus niger and mosaic symptoms in leaves of healthy-lookingEucharis andHippeastrum plants. On the basis of its host range, physical properties and serology it was identified asHippeastrum mosaic virus, a member of the potyvirus group. This was confirmed by the presence of spherical nuclear inclusions and pinwheels in different tissues of diseasedEucharis plants. The second virus with a normal particle length of 598 nm was present in both healthy-looking and mosaic-diseasedEucharis plants, and it inconsistently induced local lesions onGomphrena globosa. According to its morphology and its reaction onGomphrena, it might be identical or related toHippeastrum latent virus. Crystal-like inclusions were observed in the cytoplasm of cells of both healthy-looking and mosaic-showingEucharis leaves. As no virus-free seedlings ofEucharis were available, the virus nature of these inclusions could not be established.     

Comparison of cold GP/sealer and resin bonded obturation techniques in canine teeth in dogs

An in vitro study compared two obturation materials in the canine teeth in dogs. The teeth were instrumented with rotary instruments and obturated with either gutta percha and a sealer or resin-based materials, utilizing the gutta percha apical plug/master cone technique. Radiographs were used for evaluation of the overall appearance of the finalfill. A modified apical dye leakage method was used to evaluate the ability of each material to provide an adequate barrier to apical leakage. When comparing the two obturation materials, the differences in the radiographic appearance scores and the apical dye leakage test results were not statistically significant. The rate of apical leakage is comparable to other obturation methods that have been reported. The use of a rotary system in conjunction with the gutta percha apical plug/master cone technique is valid for the endodontic treatment of indicated teeth.