Mutational analysis of tumor suppressor gene p53 in feline vaccine site-associated sarcomas

OBJECTIVES: To investigate the role of tumor suppressor gene p53 mutation in feline vaccine site-associated sarcoma (VSS) development and to evaluate the relationship between p53 nucleotide sequence and protein expression. SAMPLE POPULATION: Formalin-fixed paraffin-embedded tissues of 8 feline VSS with dark p53 immunostaining (high p53 expression) and 13 feline VSS with faint or no staining (normal p53 expression). PROCEDURE: DNA was extracted from neoplastic and normal tissue from each paraffin block. The following 3 regions of the p53 gene were amplified by polymerase chain reaction: 379 base pair (bp) region of exon 5, intron 5, and exon 6, 108 bp region of exon 7, and 140 bp region of exon 8. Amplified p53 products were sequenced and compared with published feline p53. The p53 mutations identified were correlated with p53 mutations predicted by immunostaining. RESULTS: Neoplastic cells of 5 of 8 (62.5%) VSS that had high p53 expression harbored single missense mutations within the p53 gene regions examined.The p53 gene mutations were not detected in the 13 tumors with normal p53 immunostaining. Nonneoplastic tissues adjacent to all 21 VSS lacked mutations of these p53 gene regions. CONCLUSIONS: The p53 gene mutations were restricted to neoplastic tissue and, therefore, were unlikely to predispose to VSS. However, p53 mutations may have contributed to cancer progression in 5 of the 21 VSS. There was very good (kappa quotient = 0.67 with a confidence limit of 0.3 to 1.0), although not complete, agreement between prediction of mutation by p53 immunostaining and identification of mutations by sequencing of key p53 gene regions.     

Effects of short-term exposure to condensed tannins on adult Trichostrongylus colubriformis

Twelve parasite-naive sheep were used to study the possible direct anthelmintic effect of a condensed tannin extract (quebracho) on the population and fecundity of the intestinal nematode Trichostrongylus colubriformis. The sheep were infected with a single dose of 20,000 L3 of T colubriformis. Twenty-eight days later, six of them were drenched daily for a week with quebracho extract at 8 per cent by weight of their food intake. All lambs were then slaughtered, and their small intestines removed to estimate the worm burdens and the numbers of eggs in utero. Two days after the first drench with tannin extract the faecal egg counts of the treated sheep were approximately 50 per cent of those of the control sheep (P<0.01), but there was no further reduction with continued drenching. In the treated sheep the worm burdens and number of eggs per gram faeces per worm were reduced by 30 per cent compared with the controls (P<0.05), but the sex ratios, the number of eggs in utero and length of the worms were not affected by drenching with tannin.     

Can an increased intake of metabolizable protein affect the periparturient relaxation in immunity against teladorsagia circumcincta in sheep?

Within the overall hypothesis that the periparturient relaxation of immunity (PPRI) to gastrointestinal parasites has a nutritional basis, we studied whether an increased intake of metabolizable protein (MP) could affect the expression of immunity to Teladorsagia (Ostertagia) circumcincta of twin-bearing and -rearing Greyface ewes. Two sets of iso-energetic diets were formulated to provide either 85% (L-) or 130% (H-) of the MP requirements during the last 6 weeks of pregnancy (-P) and the first 6 weeks of lactation (-L). Thirty ewes were allocated to LP or HP. Six ewes of each group were slaughtered after lambing (S(0)); the remaining 24 ewes of each group were allocated to either LL or HL, thus creating four treatment combinations during lactation (LP/LL, LP/HL, HP/LL and HP/HL; n=12). Six ewes of each treatment combination were slaughtered at Week 3 (S(3)) or at Week 6 (S(6)) in lactation.The HP ewes were heavier at lambing, produced heavier lambs, had lower faecal egg counts (FECs), a lower concentration of plasma pepsinogen, a higher concentration of plasma albumin during late pregnancy and more abomasal globule leukocytes (GLs) but similar worm burdens at S(0) compared to the LP ewes. The LP/HL and HP/HL ewes had a higher calculated milk production than the LP/LL and HP/LL ewes. FECs increased for each treatment combination during the first 3 weeks of lactation. This increase concurred with fewer abomasal GLs at S(3) compared to S(0). The LP/HL and HP/HL ewes had a higher proportion of immature worms and more abomasal GLs than the LP/LL and HP/LL ewes at S(6). The FECs continued to increase during the second 3 weeks of lactation for the LP/LL ewes only, which concurred with an elevated plasma pepsinogen concentration and an absence of abomasal GLs at S(6). The plasma pepsinogen concentration decreased rapidly for the LP/HL ewes during lactation. We conclude that an increased intake of MP could enhance the expression of immunity to T. circumcincta of twin-bearing and -rearing Greyface ewes.     

Spongiform encephalopathy in an arabian oryx (Oryx leucoryx) and a greater kudu (Tragelaphus strepsiceros)

Clinical, pathological and epidemiological details of scrapie-like encephalopathies are described in an arabian oryx and a greater kudu. Clinical signs included ataxia and loss of condition with a short, progressive clinical course (22 and three days, respectively). Histopathological examination of the brains revealed spongiform encephalopathy characteristic of that observed in scrapie and bovine spongiform encephalopathy (BSE). It seems probable that these cases have a common aetiology with BSE. Scrapie-like spongiform encephalopathies have now been described in five species of exotic artiodactyls in Britain indicating a, hitherto inapparent, wider range of ruminant species as natural hosts for these diseases.     

抗氧化剂与基因表达

近来 ,对日粮中起抗氧化作用物质的兴趣越来越大。抗氧化物质可降低心血管病、癌症的发病率 ,而这些疾病的发生与自由基介导的氧化反应有关 ,并可被抗氧化剂抑制。对自由基的早期研究结果发现 ,自由基可损害细胞 ,导致细胞变性和突变 ( Gey,1 987;Slater,1 985)。近来集中抗氧化剂保护细胞对抗自由基的机制。日粮中抗氧化剂对组织中自由基活性有重要调节作用 ,但对其机制还所知甚少。许多研究者认为多摄取抗氧化剂如VC、VE、β-胡萝卜素 ,使组织中抗氧化剂浓度升高对细胞有利 ,但有研究者对此提出疑问。Woodal( 1 996)在一个精确控制添加…