Spatial stability of Avena sterilis ssp. ludoviciana populations under annual applications of low rates of imazamethabenz

Long‐term experiments were conducted in two winter barley fields in central Spain to determine the spatial stability of Avena sterilis ssp. ludoviciana populations under annual applications of low rates of imazamethabenz herbicide. Weed density was sampled every year (over 5 years in the first field and over 3 years in the second) on the same grid locations prior to herbicide application. Although weed patches were stable in their location, weed density decreased in most of the years. In the first field, the populations decreased exponentially over the 5‐year period. The rates of population decline were dependent on the initial density of the population, being higher for the central core of the patches and lower for the low‐density areas. Under the conditions present in this experiment, it was possible to reduce heavy weed patches (up to 1200 seedlings m^?2) down to relatively safe levels (18 seedlings m^?2) in a period of 3 years using a density‐specific control programme, applying low rates of herbicides when weed densities were below a given level (1000 seedlings m^?2). However, under adverse environmental conditions, half rates of the herbicide failed to control the weed populations adequately. The stability of the location of patches of A. sterilis ssp. ludoviciana suggest that weed seedling distributions mapped in one year are good predictors of future seedling distributions. However, the actual densities established each year will depend on the control level achieved the previous year and the climatic conditions present during the establishment period.     

Quantum statistical corrections to dynamic nuclear magnetic resonance

A quantum statistical treatment of the chemical exchange between molecular eigenstates or conformations revealed previously unsuspected dynamic terms in the spin Hamiltonian operator that describes fast exchange. These terms resulted from the effect of nuclear spin on rotational and vibrational relaxation. With the traditional theory, an interpretation of new carbon-13 nuclear magnetic resonance measurements of the chemical shift of methylcyclohexane in solution showed fast-exchange equilibrium constants that were inconsistent with the slow-exchange free-energy difference and were spread over a range of 30 percent for the various carbon-13 positions. Modeling of the new terms indicated that they have the correct magnitude and temperature dependence to reconcile these inconsistencies.     

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.     

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.     

Antimicrobial susceptibility of bacteria isolated from neonatal foal samples submitted to a New Zealand veterinary pathology laboratory (2004 to 2013)

AIMS: To describe antimicrobial susceptibility, and identify antimicrobial resistance (AMR), in bacteria isolated from New Zealand foals.

METHODS: A database search was performed of submissions to a veterinary pathology laboratory between April 2004 and December 2013 for bacterial culture of samples from foals <3 weeks of age. Culture and susceptibility results were compiled with demographic information. Susceptibility results were as defined for the Kirby-Bauer disk diffusion susceptibility test based on Clinical Laboratory Standards Institute guidelines. Multi-drug resistance (MDR) was defined as non-susceptibility to ≥3 of a panel of antimicrobials (ceftiofur, enrofloxaxin, gentamicin, penicillin, tetracycline, trimethoprim-sulfonamide); penicillin susceptibility was not included for Gram-negative isolates.

RESULTS: Submissions from 102 foals were examined, and 127 bacterial isolates were cultured from 64 (63%) foals. Of the 127 isolates, 32 (25%) were Streptococcus spp., 30 (24%) were Staphylococcus spp., 12 (10%) were Enterococcus spp. and 26 (21%) were Escherichia coli. Of 83 Gram-positive isolates, 57 (69%) were susceptible to penicillin. Over all isolates, 92/126 (73%) were susceptible to gentamicin and 117/126 (93%) to enrofloxacin; 62/82 (76%) of Gram-positive, and 22/42 (52%) of Gram-negative bacteria were susceptible to ceftiofur; 53/81 (65%) of Gram-positive, and 23/44 (52%) of Gram-negative bacteria were susceptible to tetracycline; 59/82 (72%) of Gram-positive, and 23/44 (43%) of Gram-negative bacteria were susceptible to trimethoprim-sulfonamide. Of 126 isolates, 33 (26%) had MDR; >1 isolate with MDR was cultured from 24/64 (38%) foals, and ≥2 isolates with MDR were recovered from 8/64 (13%) foals.

CONCLUSIONS: Multi-drug resistance, including resistance to commonly used antimicrobials, was found in bacterial isolates from foals in New Zealand.

CLINICAL RELEVANCE: The results of this study are of concern from a treatment perspective as they indicate a potential for antimicrobial treatment failure. For future surveillance of AMR and the creation of national guidelines, it is important to record more data on samples submitted for bacterial culture.     

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。     

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.     

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。