Production of an immune suppressor factor by Marek's disease lymphoblastoid cell lines

Culture fluids from Marek's disease (MD) lymphoblastoid cell lines have suppressive activity against normal and mitogen-stimulated chicken spleen and bursal cells and also against the homologous cell lines. Suppressive activity was also present in supernatants from spleen cells infected in vitro with MD virus. The suppressor factor from MD cell lines was non-sedimentable, trypsin sensitive, heat resistant and partially dialysable. Preliminary studies suggest it has a molecular weight of 20,000 daltons. Studies were also conducted on the effect of the prostaglandin inhibitors indomethacin and aspirin on the production and action of the suppressor factor. At low concentrations they have a stimulatory effect on the cell lines suggesting that they inhibit the effects of suppressor factor; however only small amounts of prostaglandin E2 were present in supernatants. Evidence was obtained that the suppressor factor may act indirectly by stimulating the production of prostaglandin by spleen cell cultures. The role of a suppressor factor in the immunosuppression observed in MD is discussed.     

Studies on the mechanism of vaccinal immunity to Marek''s disease

Current knowledge of the nature of the antigens and of the host immune responses in vaccinal immunity to Marek's disease is reviewed. It is suggested that a two-step mechanism of resistance operates. The first step involves humoral and cell-mediated responses directed against viral antigens; the second step occurs after challenge with Marek's disease virus and consists of cellmediated responses directed against tumour cells.     

Serum pharmacokinetics and tissue and milk residues of oxytetracycline in goats following a single intramuscular injection of a long-acting preparation and milk residues following a single subcutaneous injection

Separate groups of goats were used to determine drug depletion patterns in serum (n=10), tissue (n=20) and milk (n=8) following a single intramuscular (i.m.) dose of 20 mg/kg of a long-acting oxytetracycline (OTC) formulation (Liquamycin LA-200). Milk residues were also determined following a subcutaneous (s.c.) administration of the same product at the same dose. Serum samples were taken for 24 h post-treatment and tissues (fat, liver, kidney, muscle and injection site) collected at 4, 7, 14, 21 and 28 days following injection. Milk from lactating goats was collected every 12 h for 8 days following both the i.m. and s.c. treatments utilizing an intervening 5-week washout period. Residues in serum and tissue were measured using a microbial inhibition assay, while milk residues were measured using both a microbial inhibition assay and a validated HPLC method. The serum pharmacokinetic parameters of OTC in goats were determined, with a mean AUC=67.4 microg h/mL, mean terminal half-life=14.4 h, and apparent clearance=0.33 L/kg h. Tissue half-lives could not be determined with confidence because the collection times provided only two points at which residues could be measured for most tissues. Oxytetracycline residues in all goat tissue samples measured less then cattle tissue tolerance by 96 h postdosing. One-compartment model describing milk depletion data for i.m. and s.c. dosing had terminal slope half-lives of 20.1 and 36.1 h, respectively. By 96 h post-treatment none of the milk samples contained OTC residues in excess of the cattle milk tolerance (0.3 p.p.m.). For both milk and tissue, the upper-bound 99% confidence intervals for the samples taken from goats 96 h postdosing were lower than approved cow milk and tissue tolerances.     

Cryptococcosis in Gilbert's and long-nosed potoroo

Two cases of fatal cryptococcosis are described, one of Cryptococcus neoformans infection in a Gilbert's potoroo (Potorous gilbertii) and one of Cryptococcus gattii infection in a long-nosed potoroo (Potorous tridactylus). The diagnoses were confirmed by culture and specific immunohistochemistry, respectively. The long-nosed potoroo tested positive using the latex cryptococcal antigen test (LCAT), whereas the Gilbert's potoroo had a negative LCAT result despite having advanced disease of some duration. In both cases, the clinical presentation was a progressive neurologic disease associated with a central nervous system infection. Pulmonary infection was also observed in the long-nosed potoroo. Specific treatment with antifungal agents was unsuccessful in the long-nosed potoroo.     

Screening differentially expressed genes involved in apoptosis of primary cultured rat cerebellar granule neurons by mRNA differential display RT-PCR

AIM: To Screen and identify differentially expressed genes that involved in apoptosis model in rat cerebellar granule neurons (CGNs).METHODS: The rat cerebellar granule neurons were isolated and primarily cultured.Fluorescent differential display RT-PCR (FDD RT-PCR) was performed to screen differentially expressed ESTs in the apoptosis model of primarily cultured rat CGNs.ESTs were subcloned into pGEM-T EasyTM vector and then sequenced.Alignment assay in non-redunant database was applied for encoding information.Reverse Northern blotting was used to appraise the results from DDRT-PCR.RESULTS: 164 pieces of differentially expressed ESTs were obtained by FDDRT-PCR.17 of them were subcloned and sequenced.5 ESTs of 17 were confirmed to be positive results by reverse Northern blotting.CONCLUSION: DD-PCR is a rapid,simple-operation and sensitive method for screening differentially expressed genes,which would contribute to the molecular mechanisms of apoptosis/survive of CGNs.     

Scanning electron microscopic characterization of bovine coronavirus plaques in HRT cells

The ecology of cytopathic expression of bovine coronavirus (BCV) in HRT-18 cells was analyzed within virus-induced plaques by scanning electron microscopy. Virus replication was cytocidal for many HRT-18 cells, a function enhanced in the presence of trypsin. A monolayer of cells remained that imparted a characteristic turbidity to the plaque. These structurally normal, lysis-resistant cells did not stain with fluorescent antibodies specific for BCV antigens, failed to adsorb virus particles or mouse erythrocytes in contrast to the susceptible cells. The survival of cells in the plaque interior reflects a non-productively infected population with evidence of viral persistence.     

青杨楔天牛对杨树危害的研究

定量研究青杨楔天牛对白城杨的危害表明：寄生直径小于0.5cm的枝梢，侵入初期92.2%枯萎风折；寄生直径小于1.0cm的枝梢，侵入后期11.5%风折，成虫出孔后87.4%的寄生枝梢干枯风折。青杨楔天牛形成的虫瘿对枝梢的连年生长量影响时间长，影响量大。每主梢有1只和2只虫瘿其第1、2、3年连年生长量分别减少28.3%、16.4%、9.8%和42.0%、28.9%、17.2%。每侧枝上有1只和2只虫瘿其第1、2、3年连年生长量分别减少21.7%、12.1%、6.3%和34.8%、22.8%、13.8%。     

日本松干蚧疫情在吉林省发生发展趋势及治理情况分析报告

1994年，吉林省日本松干蚧分布面积256.7hm^2，到2002年，分布面积达到10867.2hm^2，呈快速扩散蔓延趋势。日本松干阶主要治理对策是：在疫情发生区，以营林抚育、封山育林、生物防治为主，以化学防治为辅，全力封锁控制疫情，严防继续扩散蔓延，努力减轻危害损失，对无防治前途的疫林进行有计划地砍伐更新；在疫情保护区，通过隔离带和检疫检查站建设，阻断日本松干蚧的自然和人为传播。     

高性能耐磨纸的研究

探索了不同的涂布量、胶粘剂的种类和用量对耐磨纸的耐磨转数、吸水高度和湿强度的影响，通过优化涂布工艺配方使耐磨纸的耐磨转数提高到7000转以上。