高致病性猪繁殖与呼吸综合征病毒引发高热综合征病因分析与防治措施

通过市场调研，分析了猪高致病性猪繁殖与呼吸综合征病毒引起高热综合征的发病原因，提出防治措施，以供广大养殖户参考。     

Antigenic stability of fimbriae of Bacteroides nodosus

Successful vaccination of sheep against footrot and attempts to eradicate the disease depend on there being a limit to the antigenic diversity of the causative bacterium, Bacteroides nodosus. Fimbrial antigenic variation was therefore investigated in vivo, both under conditions of chronic infection and under the pressure of a vaccine-induced immune response, to ascertain whether this represented an obstacle to such goals. Material was available from 5 experiments and although B. nodosus appeared to have undergone changes in its fimbrial antigens in one of these, the possibility that superinfection was responsible for the variation detected could not be ruled out because all sheep in this case were maintained at pasture. Overall, the results provided no evidence of fimbrial antigenic shift in B. nodosus in vivo and in conclusion, the survival of the organism in the sheep's foot, both in long-term natural infection and following vaccination, must therefore be related to factors other than the ability to undergo antigenic variation in order to evade the host's immune response.     

Use of the Anemon Index to evaluate the quality of analgesia during fentanyl and sevoflurane anaesthesia in pigs

Anemon I is a new monitoring system that can be used to evaluate autonomic nervous system reactivity in real time by showing a simple, easily interpretated quantitative index (0–200), the Anemon Index (AI) ( Junke et al. 2000 ). This study used the AI to evaluate the quality of analgesia during sevoflurane and fentanyl anaesthesia in pigs. Six healthy pigs, weighing 24.76 ± 3.40 kg, were induced to anaesthesia with 5% sevoflurane (SEVO) in 5 L minute^?1 oxygen. After endotracheal intubation SEVO was given at 1 MAC (2.66%) in 3 L minute^?1 oxygen. Fentanyl was infused IV at 50 µg kg^?1 hour^?1 for the first 30 minutes of anaesthesia, discontinued for 30 minutes, and then infused at 100 µg kg^?1 hour^?1 for another 30 minutes. Three mechanical noxious stimuli (needle prick, pin‐prick and pressure on the abdomen) were applied for 15 seconds at 30, 60 and 90 minutes. The AI, ECG, invasive mean arterial blood pressure (MAP), heart rate (HR), SpO₂ by pulse oximetry, tidal volume, Fe′sevo , Fe ′CO₂ and respiratory rate were recorded before induction (baseline), after induction, after intubation and extubation, and before and during noxious stimulation at 30, 60 and 90 minutes. Recovery times were recorded. Statistically significant differences were determined by anova . Spearman rank‐correlation was used to evaluate the relationship between AI and hemodynamic variables. A p‐value of < 0.05 was considered significant. A significant (p < 0.01) decrease in AI was recorded after anaesthetic induction, from 82.3 ± 21.1 to 52.7 ± 20.3. After intubation, AI increased slightly, but not significantly, to 71.7 ± 27.1. A significant (p < 0.05) increase of AI occurred after extubation. Nociceptive stimuli did not have any measurable effect either on AI or on recorded cardiovascular variables. There was no movement, respiratory changes, or any other visible response to noxious stimulation. The AI did not change significantly with the different doses of fentanyl. Respiratory depression and apnoea were seen in all animals during the fentanyl infusion; therefore, pigs received intermittent positive pressure ventilation. Anaesthesia with sevoflurane and fentanyl resulted in a significant (p < 0.001) decrease in MAP. Heart rate did not change significantly. There was no correlation between AI and cardiovascular variables (HR and MAP). Endotracheal intubation caused an increase and extubation a greater significant increase in the AI. This suggests that intubation and extubation may represent stressful events during general anaesthesia, although further studies are needed to validate the use of the AI in pigs. Sevoflurane anesthetic induction may not prevent the sympathetic stimulus caused by endotracheal intubation in pigs, as indicated by the increased AI values.     

24-Hour Secretion Patterns of Plasma Oestradiol 17β in Pony Mares in Late Gestation

The mare exhibits nocturnal uterine contractions in the last 6 days of gestation. It is hypothesized that estradiol 17β (O17β) may be associated with the nightly increase in uterine contractions. The 24‐h secretion pattern of plasma O17β was measured in 3 pony mares in late gestation to identify changes in release as the mare neared parturition. Blood was collected weekly at 08:00 hours beginning on day 240 and every third day from day 330 until delivery. Serial blood samples were collected from each mare every 30‐min for 24‐h beginning on gestation day 310 and every sixth day thereafter until parturition. Concentrations of O17β were elevated at night with lowest concentrations occurring directly before sunset (p < 0.01). The natural log of the variance was increased at sunset (p < 0.01) and was decreased during the 6‐h period immediately after sunrise. This pattern was especially evident in the 6 days that preceded parturition. The contrast between nocturnal and daytime concentrations of O17β in the last 6 days of gestation may contribute to night‐time delivery in the mare.     

Liposome-encapsulated oxymorphone prevents hyperalgesia for 7 days in a rat model of neuropathic pain

A delayed‐release formulation of liposome‐encapsulated oxymorphone (LEO) was produced using a novel dehydration–rehydration technique. Preparations were standardized spectrophotometrically against a known concentration of the drug. The purpose of this study was to test the analgesic properties of LEO in a rat model of neuropathic pain. Sprague–Dawley rats were divided into control (non‐neuropathic) and test (neuropathic) groups. Control and test groups were administered one SC injection of (i) vehicle liposomes (negative control treatment); (ii) liposome‐encapsulated morphine, 2.8 mg kg^?1 (positive control treatment); or (iii) LEO, 1.2 mg kg^?1. All treatments were administered after baseline thermal withdrawal latencies (TWL) were determined (9.2 ± 0.39 seconds (mean ± SEM)). Test groups then underwent sciatic ligation to induce neuropathic pain. TWL were determined in all six groups (n = 8) daily for 1 week. In a separate group of age‐matched rats, blood (0.3 mL from the jugular vein) and urine (1–2 mL via metabolism cages) were collected daily for 7 days after administration of LEO (1.2 mg kg^?1). TWL did not change in the control rats given liposome‐encapsulated sucrose or morphine. There was a small increase (p = 0.04) in TWL in control rats given LEO, likely as a result of the relatively higher dose of oxymorphone compared with morphine based on receptor affinity. TWL in test rats given blank liposomes decreased significantly (p < 0.001) by day 4 (7.1 ± 0.5 seconds), with a maximal decrease by day 7 (5.1 ± 0.36 seconds), indicating development of full hyperalgesia. In contrast, rats given liposome‐encapsulated morphine or oxymorphone had no change in TWL at day 4, indicating that these preparations prevented hyperalgesia after a single injection. This treatment effect persisted through day 7. Serum concentrations of oxymorphone after a single injection of LEO peaked at 4 hours (6.8 ± 0.82 ng mL^?1) and were detectable through day 4 (0.98 ± 0.003 ng mL^?1), while urine concentrations of drug were detectable through day 7. This result suggests that oxymorphone metabolites might have been responsible for the protracted analgesic response. The encapsulation efficiency of oxymorphone using this novel technique was approximately 96%. In conclusion, liposome encapsulation of oxymorphone proved to be an efficient mechanism to provide a delayed‐release formulation of this opioid. This single dose of subcutaneously administered liposome‐encapsulated oxymorphone was effective in preventing hyperalgesia for 7 days in this animal model of neuropathic pain.     

烟田杂草防除试验研究

采用5种地膜和2种除草剂进行烟田除草试验。结果金都尔地膜、玉溪除草膜、绿色除草地膜和黑色除草地膜相对于普通白膜而言,对单子叶的防除效果分别为93．22％,95．27％,95．42％,99．83％,对双子叶的防除效果分别为43．12％,52.20％,73.85％,77．27％。敌草胺2次施药的防效明显优于1次施药。不同除草膜对地温的作用存在差异性。     

High-Energy Charged Particles in the Innermost Jovian Magnetosphere

The energetic particles investigation carried by the Galileo probe measured the energy and angular distributions of the high-energy particles from near the orbit of Io to probe entry into the jovian atmosphere. Jupiter's inner radiation region had extremely large fluxes of energetic electrons and protons; intensities peaked at approximately2.2RJ (where RJ is the radius of Jupiter). Absorption of the measured particles was found near the outer edge of the bright dust ring. The instrument measured intense fluxes of high-energy helium ions (approximately62 megaelectron volts per nucleon) that peaked at approximately1.5RJ inside the bright dust ring. The abundances of all particle species decreased sharply at approximately1.35RJ; this decrease defines the innermost edge of the equatorial jovian radiation.     

Evaluation of Trypsin Treatment on the Inactivation of Bovine Herpesvirus Type 1 on In Vitro Produced Pre-implantation Embryos

The aim of this study was to evaluate the efficiency of trypsin treatment on the inactivation of bovine herpesvirus type 1 (BoHV-1) on in vitro produced by fertilization and artificially infected bovine embryos. Bovine embryos on day 7 were exposed with 10 μl of BoHV-1, Los Angeles strain 10^7.5 TCID. These embryos and control embryos were divided in two groups: submitted to the sequential washes or to the trypsin treatment according to the International Embryo Transfer Society (IETS) guidelines. The embryos and the last washing drop of each group were used as inoculum to infect Madin Darby bovine kidney (MDBK) cells and submitted to nested PCR reaction using the primer that encodes the gene conserved region of virus glycoprotein gB. The data have shown that the control embryos and their last washing drop were negative. The exposed embryos that were treated with trypsin have shown positive results on the n-PCR and MDBK culture, and their last washing drop were negative. Our data have demonstrated that the trypsin treatment was not able to eliminate the BHV-1 of the embryos, suggesting an interaction between virus and embryo.