The impact of staphylococcal mastitis on the level of milk IL-6, lysozyme and nitric oxide

Mammary gland secretions derived from secretory cows infected with coagulase +ve Staphylococcus spp. was examined for the expression of IL-6, production of lysozyme and NO(x). The examined cows reflected 25 cases of subclinical mastitis and 15 cases of clinically mastitic animals. The IL-6 concentration in the subclinical animals was significantly higher (30.8 ng/ml) than the clinically manifested animals (18.0 ng/ml) and the normal cows (5.2n g/ml). On the other hand the level of lysozyme although significantly higher than the normal cows (6.9 microg/ml) yet its level in the subclinical animals (11.2 microg/ml) was lower than that estimated in the clinical animals (15.6 microg/ml). Similarly, the level of NO(x) in the normal animals was found to be 5.6 microM/ml to increase to 6.2 microM/ml in the subclinical mastitic animals and to significantly increase further to 11.5 microM/ml in the clinically affected cows. These results suggest the promising use of whey IL-6, lysozyme or/and NO concentration variabilities as prognostic parameters on the degree of the commencement of mastitis in cows.     

Androgens modulate growth hormone-releasing factor-induced GH release from bovine anterior pituitary cells in static culture.

Static primary cultures of bovine anterior pituitary (AP) cells were utilized to study the effect of sex steroids on basal growth hormone (GH) and GH-releasing hormone (GRF)-stimulated release of GH. The AP cells (5 x 10(5) cells/well) were allowed to attach for 72 hr and become confluent before treatments were imposed. Cells were incubated for an additional 24, 48 or 72 hr with either estradiol-17 beta (E2, 10(-11) to 10(-8) M), testosterone (T, 10(-8) to 10(-5) M), dihydrotestosterone (DHT, 10(-9) to 10(-6) M) or 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol, 10(-11) to 10(-8) M). Media were collected every 24 hr and GH concentrations determined by RIA. Incubation of calf AP cells with gonadal steroids did not affect (P > 0.05) basal GH released at 24, 48, or 72 hr. In another experiment, calf AP cells were incubated with the same concentrations of the steroids for 24 hr, media harvested, cells washed and challenged in serum-free media for 1 hr with bovine GRF 1-44-NH2 (10(-8) M). In non-steroid treated wells, GRF increased (P < 0.05) GH from 58 to 134 ng/ml. Incubation with E2 or 3 alpha-diol did not affect (P > 0.05) GRF-induced GH release; however, preincubation with T (10(-5) M) and DHT (10(-9), 10(-8) and 10(-7) M) increased (P < 0.05) GRF-induced GH release above control concentrations (195, 235, 190 and 185 ng/ml, respectively). At the doses tested, sex steroids did not affect basal release of GH, but androgens increased responsiveness of somatotropes to GRF.     

Bioactivation of zearalenone by porcine hepatic biotransformation

Zearalenone (ZEA) is a resorcylic acid lactone derivative produced by various Fusarium species that are widely found in food and feeds. The structure of zearalenone is flexible enough to allow a conformation able to bind to mammalian oestrogen receptors, where it acts as an agonist. Using oestrogen-dependent Human Breast Cancer (MCF-7) cells, the oestrogenic activity of zearalenone and its derivatives were compared using 17 beta-oestradiol as a positive control. The results obtained demonstrate that the oestrogenic potency of ZEA derivatives could be ranked in the following order: alpha-zearalenol > alpha-zearalanol > zearalenone > beta-zearalenol. Since pigs have been reported to be among the most sensitive animal species, biotransformation studies with pig liver subcellular fractions were conducted. These studies indicated that alpha-zearalenol is the main hepatic metabolite of zearalenone in pigs, and it is assumed that 3 alpha- and 3 beta-hydroxysteroid dehydrogeneases are involved in the hepatic biotransformation, since the formation of alpha-zearalenol and beta-zearalenol could be inhibited by prototypic substrates for either enzyme. The bioactivation of ZEA into the more active alpha-zearalenol seems to provide a possible explanation for the observed high sensitivity of pigs towards feeding-stuffs contaminated with the mycotoxin.     

Determination of species-specific sequences of superoxide dismutase A encoding gene sodA and chaperonin 60 encoding gene cpn60 for identification and phylogenetic analysis of Streptococcus phocae

Species-specific PCR tests, based on the manganese-dependent superoxide dismutase A encoding gene (sodA) and the chaperonin 60 encoding gene (cpn60), were developed for the identification of Streptococcus phocae, a bacterial pathogen of seals. The selection of both oligonucleotide primer pairs was performed after amplification and sequencing of internal parts of both genes using universal oligonucleotide primers. The sequence studies of both genes additionally confirmed that S. phocae could taxonomically be classified to the pyogenic group of the genus Streptococcus.     

Very Virulent Infectious Bursal Disease Virus in Egypt: Epidemiology,Isolation and Immunogenicity of Classic Vaccine

Infectious bursal disease (IBD) is still a significant threat facing the Egyptian poultry industry. In this study, eight very virulent IBD viruses (vvIBDV), originating from acute IBD outbreaks recorded in lower and upper Egypt, were studied with respect to their ability to replicate in cell culture, antigenicity and immunogenicity of classic vaccine. Six continuous cell lines and one primary cell culture were tested for replication of the vvIBDVs. None of the vvIBDV isolates could be adapted to BGM-70, Vero, BHK, RK-13 or MDBK cell lines or chicken embryo fibroblast cells after six blind passages. Serological typing with three neutralizing monoclonal antibodies showed antigenic variation among vvIBDVs. The immunogenicity induced by graded doses of classic-intermediate vaccine in both IBD-resistant (Mandarah) and susceptible (Gimmizah) Egyptian chickens was investigated. The protection of the tested doses was evaluated by measurement of the serological response and resistance to vvIBDV challenge 10 days post vaccination. Similar antibody responses to the vaccine were generated over a wide (100-fold) dose range. It was concluded that single vaccination, by eye drops, with classic-intermediate vaccine (1 x) could protect chickens against clinical disease and mortality. However, the immune responses generated by 1 x, 10 x or 100 x vaccine doses did not protect against bursal damage following challenge. This finding points to the highly invasive nature of the prevailing vvIBDVs in Egypt.