临床分离食品动物源多重耐药大肠杆菌耐药分子特征研究

本研究从主动外排机制、膜孔蛋白缺失及氟喹诺酮类药物作用靶位改变等几个方面探讨,临床分离的20株动物源性多重耐药大肠杆菌的耐药分子特征。实验结果表明,20株临床分离大肠杆菌gyrA83、gyrA87、parC80的突变率分别为95％、85％、55％。gyrA和parC共同突变的有11株,突变率为55％;20株多重耐药菌大肠杆菌普遍存在主动外排机制,主要介导对部分氨基糖苷类、四环素、氟苯尼考和氟喹诺酮类药物耐药,当添加外排泵抑制剂PAβN后多数菌株庆大霉素、新霉素、四环素、氟苯尼考及氟喹诺酮类药物的MIC都降低了2倍～256倍。利用建立的ELISA方法检测外排泵AcrA蛋白的表达水平,结果证实所有,临床分离菌外排泵表达都增高;20株分离大肠杆菌中,部分菌株缺失OmpC或OmpF蛋白,同时缺失这两个蛋白的只有3株。部分菌株OmpF蛋白条带附近存在有多重耐药相关蛋白（Mar）。本研究结果揭示多重耐药大肠杆菌对常用抗菌药物高水平的耐药表型是主动外排机制、药物作用靶位的改变、外膜通透性的改变及其它机制共同作用的结果。     

过瘤胃氯化胆碱在泌乳奶牛上的应用

将14头荷斯坦奶牛完全随机分为2组,每组7头。试验组从围产前期开始至产后1个月内每天每头饲喂10 g过瘤胃氯化胆碱,测定所有供试牛产后第1个泌乳月内日均产奶量;同时分别在产前1周、产后24 h、产后1、2、3、4周共6个时间点采血,测定血清中血糖、D₃ 羟丁酸、血脂（甘油三酯、总胆固醇, 包括高密、低密、极低密）、谷丙转氨酶、谷草转氨酶的含量。结果表明,与对照组相比,饲喂过瘤胃氯化胆碱的奶牛产后第1个月内日均产奶量比对照组提高1.7%（P>0.05）;围产期及泌乳初期血糖能维持在相对稳定的水平;D₃ 羟丁酸含量降低（P>0.05）,血脂、谷丙转氨酶、谷草转氨酶均无显著差异（P>0.05）。因此,围产期饲喂过瘤胃氯化胆碱能缓解奶牛产后能量负平衡状态,预防酮病,帮助奶牛快速恢复健康,提前进入产奶高峰期,提高牛场经济效益。     

不同施肥时期及施肥量对草地早熟禾生长发育特性的影晌

研究了不同施肥时期及施肥量对草地早熟禾生长发育特性的影响.研究表明:返青期加强施肥有利于草地早熟禾的生长,同时,可显著提高植株密度以及干物质的积累量.     

Influences of Vit-E on the mtDNA damage and Ca2+ homostasis of hippocampus and antioxidative ability in brain of aging mice induced by D-galactose

AIM: To study the influences of vitamin E (Vit-E) on the mtDNA damage and Ca²⁺ homeostasis in hippocampus and antioxidative ability in aging brain induced by D-galactose.METHODS: D-galactose (1 000 mg·k^-1·d^-1 ) was injected into mice hypodermically for 8 weeks to induce aging animal model, and Vit-E (100 mg·kg^-1; 250 mg·kg^-1) was administered for 6 weeks by ig at the 3rd week of making model. After Vit-E treatment for 8 weeks, water maze test was used to determine the ability of mice’s learning and memory. The activities of glutathione peroxidase (GSH-Px) and succinate dehydrogenase (SDH), the content of nitric oxide (NO) and activity of nitric oxide synthase (NOS) in the brain tissue were detected separately. Fura-2/AM, double-wave-length fluorospectrophotometer and PCR method were used to measure the concentration of calcium ion and mtDNA mutation in the hippocampus cells.RESULTS: Administration of Vit-E improved significantly the ability of learning and memory in model mice, inhibited the activity of NOS and decreased the amount of NO, and increased the activities of GSH-Px and SDH respectively in brain tissues, decreased the concentration of calcium ion (P<0.01, P<0.05), and prevented the damage of mtDNA in hippocampus.CONCLUSION: Vit-E can enhance the antioxidative ability, regulate the homeostasis of Ca²⁺ and inhibit the damage of mtDNA caused by oxidative stress in aging brain, and improve the ability of learning and memory in aging mice.     

Mechanisms for a decrease in mortality of LPS-challenged mice by rhynchophylline

AIM: To observe effect of rhynchophylline （Rhy） on mortality and organ injury in endotoxemic mice and further investigate the mechanisms of its actions. METHODS: Male mice were randomly assigned into control, LPS, Rhy +LPS and Rhy group, and injected subcutaneously with normal saline (0.05 mL/10 g), or rhynchophylline once a day for 3 d, 1 h after subcutaneously treatment on day 3, LPS (20 mg/kg) or normal saline was injected intraperitoneally. Survival rate was recorded every 12 h for 6 d. In another experiment, 12 h after LPS injection, the left lung and intestine tissue sections were prepared for histological analysis and the right lung were used to determine the ratio of wet to dry lung tissue weight (W/D),the serum was collected to detect the concentrations of alanine aminotransferase（ALT）, aspartate aminotransferase (AST ), bloodureanitrogen (BUN) and creatinine (Cr). In addition, the concentrations of tumor necrosis factor-α (TNF-α), interleukin-1β(IL-1β) and interleukin-10 (IL-10) in serum at 2 h after LPS challenge were detected by enzyme-linked immunosorbent assay. The concentration of NO in serum at 8 h was detected by enzymic method. The effect of Rhy on survival rate of mice subjected to cecal ligation and puncture (CLP) was also observed. RESULTS: Mortality of mice challenged with LPS alone was higher significantly than that in control at 24 h after LPS challenge, pretreated with Rhy at a dose of 8 or 16 mg/kg increased markedly the survival rate of LPS-challenged mice. However, Rhy at a dose of 8 mg/kg significantly increased mortality of mice subjected to CLP. In the histological analysis, severe inflammation was observed both in the lung and intestine tissues in the LPS group. LPS elevated lung W/D, the levels of ALT, AST, BUN, Cr, TNF-α, IL-1β, IL-10 and NO in serum. Pretreatment with Rhy had no obvious improvement in the lung and intestine tissue injury, and no significant depression in the lung W/D and the serum levels of ALT, AST, BUN, Cr, IL-1β, IL-10 and NO, but decreased the level of TNF-α in serum significantly in LPS -treated mice. CONCLUSION: Pretreatment with Rhy reduces the mortality in endotoxemic mice, but not decrease the mortality of mice challenged with CLP, at least in part, through inhibiting the synthesis and secretion of TNF-α.     

Effects of panaxadiol saponin on TLR2 and TLR9 mRNA expression in LPS induced shock rats

AIM: To explore the molecular mechanism of panaxadiol saponin (PDS) by observing Toll like receptor (TLR) 2 and TLR9 mRNA expression induced by lipopolysaccharide (LPS).METHODS: Rats were divided into LPS, LPS+PDSL, LPS+PDSM and control group, respectively. Nitric oxide synthase (NOS) activity, nitric oxide (NO) content, LPO content, SOD activity and TLR2 and TLR9 mRNA expression were assayed 4 h after intravenous injection of LPS. RESULTS: NOS activity, NO content, LPO content of LPS+PDSL group and LPS+PDSM group were significantly lower than those in LPS group. TLR2 mRNA expression in the liver tissue of LPS+PDSL group and LPS+PDSM group was decreased compared with LPS group.CONCLUSION: PDS has a protective effect on liver tissues by triggering the down-regulation of TLR2 expression, reducing NOS activity, and NO content.     

Role of EETs downregulation in obesity-related hypertension induced by a high fat diet

AIM: To study the effect of renal epoxyeicosatrienoic acids (EETs)on juvenile rats with obesity related hypertension induced by high fat diet.METHODS: Sprague-Dawley male rats were fed with high fat diet from 3-week old. The changes of weight and sBP between the rats of high fat diet and normal diet were compared. EETs activity was analyzed with RP HPLC and Western blotting in different parts of kidney.RESULTS: Weight and sBP increased in high fat diet group at the eighth and eleventh weeks ［(328±23)g vs (273.0±21.0)g, (153.0±8.6)mmHg vs (134.0±7.7)mmHg, P<0.05］. No significant change of the EETs activity of renal microvessels between two groups was observed. The EETs activity in cortex and papilla decreased in high fat diet group compared with that in normal diet group ［(75.4±9.2)nmol·g-1·min-1 vs (138.1±10.3)nmol·g-1·min-1, (55.8±6.2)nmol·g-1·min-1 vs (121.6±11.3)nmol·g-1·min-1, P<0.05］, and this was confirmed by Western blotting.CONCLUSION: These results demonstrate that juvenile rats with obesity related hypertension induced by high fat diet might be related to the downregulation of EETs activity in cortex and papilla.     

Determination of net energy content of soybean oil fed to growing pigs using indirect calorimetry

The objectives of this experiment were: (i) to determine the net energy (NE) of soybean oil (SBO) fed to growing pigs using indirect calorimetry (IC); and (ii) to evaluate the effects of inclusion rate of SBO on heat production, oxidative status and nutrient digestibility in growing pigs. Eighteen growing barrows were allotted to three diets based on completely randomized design with six replicate pigs (period) per diet. Diets included a corn‐soybean meal basal diet and two test diets containing 5% or 10% SBO at the expense of corn and soybean meal. During each period, pigs were individually housed in metabolism crates for 14 days, including 7 days to adapt to feed, metabolism crate and environmental conditions. On day 8, pigs were transferred to the open‐circuit respiration chambers for measurement of daily O₂ consumption and CO₂ and CH₄ production. During this time, pigs were fed one of the three diets at 2.4 MJ metabolizable energy/kg body weight (BW)^0.6/day. Total feces and urine were collected and daily total heat production (THP) was measured from days 9 to 13 and fasted on day 14 to evaluate their fasting heat production (FHP). The results show that trends of decreased apparent total tract digestibility of neutral detergent fiber (linear, P = 0.09) and acid detergent fiber (linear, P = 0.07) were observed as the content of dietary lipids increased. The average THP for the three diets were 1326, 1208 and 1193 kJ/kg BW^0.6/day, respectively. The FHP of pigs averaged 843 kJ/kg BW^0.6/day and was not affected by diet characteristics. A reduction of the respiratory quotients in the fed state as the inclusion level of SBO increased was observed. In conclusion, the NE values of SBO we determined by indirect calorimetry were 33.45 and 34.05 MJ/kg dry matter under two inclusion levels. THP could be largely reduced when SBO is added in the feed, but the THP of SBO included at 5% in a corn‐soybean meal diet is not different from the THP of SBO included at 10%.     

Acute polyneuromyopathy with respiratory failure secondary to monensin intoxication in a dog

Objective

To describe a successfully managed case of polyneuropathy and respiratory failure secondary to presumed monensin intoxication.

Case Summary

A 9‐month‐old Australian Shepherd was evaluated for progressive generalized weakness and respiratory distress. Several days preceding presentation, the dog was seen playing with a monensin capsule, and had free access to a barn where the product was stored and where chewed capsules were subsequently found. The dog was presented with flaccid tetraparesis, hyperthermia, and severe respiratory distress. Bloodwork and urinalysis revealed marked increase in serum creatine kinase concentration and presumed myoglobinuria. Cardiac troponin I level was markedly increased. Management included mechanical ventilation for 5 days, fluid‐therapy, active cooling, antimicrobial therapy, analgesia, gastroprotectants, antiemetics, enteral feedings, continuous nursing care, and physiotherapy. Intravenous lipid rescue therapy was administered with lack of improvement in respiratory function and muscle strength. The patient completely recovered and was discharged after 12 days of hospitalization.

New or Unique Information Provided

Monensin intoxication should be considered in the differential diagnosis of acute polyneuromyopathy and respiratory failure in dogs with access to this compound. Respiratory failure secondary to monensin intoxication does not necessarily carry a poor prognosis if mechanical ventilation can be provided as a bridge until return of respiratory function is achieved.