缬沙坦对动脉粥样硬化兔血清IL-8和TNF-α水平的影响

目的：研究缬沙坦对动脉粥样硬化兔血清IL-8和TNF-α水平的影响。方法：将30只实验兔随机分为3组,每组10只,即正常对照组：喂以普通饲料;高脂饮食组：喂以高脂饮食（含15%蛋黄粉,0.5%胆固醇和5%猪油的饲料）6周,后给予10 ml/d生理盐水4周;药物干预组：喂以高脂饮食6周,后给予缬沙坦（10 mg/kg/d）治疗4周。饲养6周和10周时分别经兔耳缘静脉取血,通过酶联免疫法检测各组兔血清中IL-8和TNF-α的水平。结果：饲养第6周时,高脂饮食组和药物干预组兔血清TNF-α和IL-8水平均较正常对照组明显升高,差异均具有统计学意义（P〈0.05）,而高脂饮食组与药物干预组比较差异无统计学意义（P〉0.05）。饲养第10周时,即缬沙坦干预4周后,药物干预组与建模6周时比较,血清TNF-α及IL-8水平均明显下降,差异具有统计学意义（P〈0.05）,且与高脂饮食组比较,血清TNF-α及IL-8水平亦明显下降,差异具有统计学意义（P〈0.05）。结论：动脉粥样硬化时,血清IL-8和TNF-α升高,缬沙坦能明显降低动脉粥样硬化中IL-8和TNF-α水平,从而发挥抗动脉粥样硬化作用。     

制备低剂量四氯化碳诱导小鼠慢性肝损伤模型的探讨

目的：通过注射低剂量四氯化碳（ carbon tetrachloride ,CC14）建立B/C小鼠肝损伤模型。方法正常B/C小鼠随机分为正常对照组、油对照组、CCl4模型组。正常对照组常规饲养;油对照组腹腔注射鲁花花生油（10μL/g,1次/3天,连续6周）;CC14模型组腹腔注射0.5％CC14（10μL/g,1次/3天,连续6周）。第6周,各组小鼠检测血清AST、ALT浓度,HE及Masson染色后观察小鼠肝脏结构、细胞形态及纤维化程度。结果第6周CCl4模型组小鼠血清ALT（P＝0.00）、AST（P＝0.00）浓度极显著性增高,HE及Masson染色显示CCl4模型组小鼠肝上皮细胞呈广泛性空泡样变及大量坏死,肝小叶内出现明显的条索样纤维增生,其纤维化程度评分显著性升高（P ＝0.00）,纤维显色积分光密度值极显著性增高（P ＝0.00）。结论注射低剂量CCl4可以诱导B/C小鼠肝损伤模型,实验模型具备肝损伤和肝纤维化病理特征。     

大鼠成年前异常生活环境对其成年后恐惧记忆的影响(英文）

为了探讨早期饲养环境对成年后大鼠条件化恐惧的影响,实验采用巴氏恐惧条件化的方法对不同饲养环境下的大鼠进行了行为检测。具体操作为：把断奶后的大鼠饲养在3个不同的人工控制的环境中（丰富环境、社群环境和贫瘠环境）;8周后进行恐惧条件化训练和测试（指标为僵直百分比）,以及检测不同饲养环境下的大鼠的体重、自发活动和足部电击敏感性。结果显示：与社群组相比,丰富组的大鼠条件化僵直水平明显增加,而贫瘠组的明显减少;丰富和贫瘠环境明显的影响了大鼠的体重;不同环境对自发活动和足部电击敏感性没有影响。这些结果说明幼年期的丰富环境能提高成年后大鼠的由声音诱发的条件化恐惧反应,而贫瘠环境则削弱了这种反应。     

高浓度七氟醚通过抑制VEGF/PI3K/AKT信号通路诱导神经干细胞凋亡的研究

目的探讨妊娠中期的七氟醚暴露对神经干细胞凋亡过程的影响和作用机制。 方法将孕中期大鼠随机分为3组,每组48只孕鼠：对照组,低浓度七氟醚组,高浓度七氟醚组。在妊娠第14天,以2﹪或3.5﹪七氟醚麻醉怀孕大鼠2?h。通过免疫荧光检查神经干细胞凋亡,收集麻醉后6、24和48?h以及出生后第0天（P?0）,第14天（P?14）和第28天（P?28）的脑组织进行Nestin-TUNEL免疫荧光双标染色以及Nestin、血管内皮生长因子（VEGF）和磷酸肌醇3-激酶（PI3K）AKT通路相关蛋白的免疫印迹检测。采用单因素方差分析和Bonferroni事后检验进行统计学分析。 结果麻醉后6、24和48?h以及P?0,P?14和P?28,脑组织中Nestin和TUNEL阳性细胞的百分比增加[6?h：对照组0.91±0.07,低浓度组1.01±0.08,高浓度组2.62±0.21（F?=?399,P?相似文献   

以黑丝羽乌骨鸡为供体制作家鸡嵌合体的研究

以黑丝羽乌骨鸡（BS）为供体,自来航鸡（WL）为受体,进行了BCs嵌合体制作技术研究。结果表明：（1）“黑羽”对“白羽”、“丝羽”对“片羽”为完全隐性,可以在供体与嵌合体测交中,后代是否出现这些特征作为种系嵌合体判断依据。（2）供体的其它表型,对受体属于完全或不完全显性,可以作为体细胞嵌合体判断依据。（3）通过改进嵌合体制作技术,嵌合体雏鸡的出壳率为40％（29／73）,其中据羽色判断的嵌合体率为18％（13／73）;以黑羽为依据选择体细胞嵌合体雏鸡,10只饲养至720d,其中60％（6／10）的嵌合体外观基本不变（其余的换羽后褪去黑羽）;嵌合体鸡与供体测交,以黑羽、灰羽和丝羽判断,8只嵌合体鸡的种系传递率分别为2．5％-71．4％、5．5％～14．3％以及1．7％～10．5％。首次利用BS鸡资源,建立了多表现型嵌合体模型,为家鸡嵌合体技术深入研究提供了方便的检测方法。     

两种可摘局部义齿戴用前后语音效果的对比研究

目的：对上颌肯氏I类牙列缺损可摘局部义齿戴用前后的临床语音适应效果做出客观评价。方法：对30例上颌肯氏I类牙列缺失患者在义齿初戴前、初戴时、初戴后的1、2、4、8用语音变化规律进行分析。结果：辅音／j／：在塑料组,在初戴后2．4、8周与初戴时F2有统计学差异（P〈0．05）;在初戴时与初戴前相比F2也有统计学差异（P〈0．05）。初戴后1周也有统计学差异（P〈O．05）;两组同一时间内比较,/j/的F2在初戴时有统计学差异（P〈0．01）。／sh／音：在初戴时与初戴后2、8周F1有统计学差异（P〈0．05）。/z／音：在塑料、铸造两组中,F1、F2在初戴前、后2、4、8周均有统计学差异（P〈0．05）。结论：可摘局部义齿基托厚度主要影响的发音部位是硬腭前部,在临床上,减少硬腭区基托厚度,对临床修复有较好的指导意义。     

鸡马立克氏病抗性选育实验

马立克氏病（MD）是严重危害养鸡业发展的急性传染病。从1996年起,采用血型基因检测和后裔马立克氏病病毒（MDV）攻击选留强抗性亲本途径开展了MD抗性选育实验。结果表明：（1）亲本4上发代No.614血型基因检测阳性率逐代上升。由F0的68．8％,F1的77．3％,F2的81．8％到F3的90．5％。（2）F2－F4雏鸡10日龄MDV攻击,60日龄死亡率,亲本对No.614抗血清呈阳性反应的实验组3个世代分别是25．8％,69．2％和29．4％;亲本对No.614抗血清呈阴性反应的对照组相应是30．6％,81．0％和52．9％,实验组鞭显著低于对照组（P＜0．01或P＜0．05）。（3）实验期间F2－F4雏鸡9个内脏器官组织肿瘤病变率,实验组3个世代分别是87．6％,83．3％和58．8％;对照组相应为88．1％,84．5％和70．6％;两者比较除个别世代,个别器官实验组低于对照组（P＜0．05）外,多数没有显著差异（P＞0．05）。并对实验结果及MD抗性的遗传控制进行了讨论。     

鸡新城疫口服DNA疫苗的安全性、稳定性与免疫效力

将含新城疫病毒（NDV）F₄₈E₉株融合蛋白（F）基因的真核表达质粒pcDNA3-F的减毒鼠伤寒沙门氏菌ZJ111株（ZJ111/pcDAN3-F）口服接种小鼠和雏鸡。结果表明：利用该减毒株作为载体传递DNA疫苗具有相对安全性。用酶切和PCR鉴定法证实在体内外无抗生素存在的条件下重组质粒在受体菌ZJ111菌株内比较稳定。ZJ111/pcDAN3-F以每羽10⁸cfu免疫雏鸡,2周后二免,二免后4周攻击致死剂量的强毒株F₄₈E₉,观察其免疫效力。结果表明：重组ZJ111/pcDNA3-F菌株不仅能诱导雏鸡产生抗NDV抗体,而且能诱导法氏囊B淋巴细胞和胸腺T淋巴细胞的增殖反应,对强毒株攻击的保护率为66.7%,高于pcDNA3-F裸质粒DNA疫苗注射免疫组（50%）。上述结果初步提示减毒沙门氏菌为载体传递DNA疫苗具有良好的安全性、稳定性和免疫原性,为研制低成本、实用化的口服禽类DNA疫苗奠定了基础。     

硫胺素、核黄素和烟酰胺对大鼠体重增长及脂代谢影响的实验研究

目的：B族维生素以辅酶的形式参与糖、脂肪和蛋白质代谢,本文观察硫胺素、核黄素和烟酰胺补充对高脂饲料诱导大鼠肥胖的影响。方法：采用预防肥胖模型法,2×2×2析因设计分为8组：高脂对照组（F0组）,高脂＋硫胺素（F1组）,高脂＋核黄素（F2组）,高脂＋烟酰胺（F3组）,高脂＋硫胺素＋核黄素（F4组）,高脂＋硫胺素＋烟酰胺（F5组）,高脂＋核黄素＋烟酰胺（F6组）,高脂＋硫胺素＋核黄素＋烟酰胺（F7组）,每组12只大鼠,给予高脂饲料喂养,同时硫胺素（100mg／kgbw／d）、核黄素（100mg／kgbw／d）、烟酰胺（250mg／kgbw／d）灌胃,另设正常对照组（C组）12只,普通饲料喂养,自来水灌胃,15周后,分析其体重、摄食量、体脂重量、血脂等实验前后的变化情况及各组动物之间的差别。结果：经过15周喂养后,高脂喂养大鼠体重比正常对照组平均增加了15．7％;而补充烟酰胺（F3）及联合硫胺素（F5）或核黄素（F6）以及三者联合补充（F7）组高脂喂养大鼠与高脂对照组（F0）相比,体重分别降低了35．0％,30．0％,30．1％和30．6％（P值均小于0．05）;甚至比正常对照组大鼠平均体重分别下降了22．8％,17．0％,17．0％和17．7％（P值均小于0．05）;而补充核黄素或和硫胺素组大鼠体重没有明显增加或降低（P值均大于0．05）。血脂分析结果显示高脂喂养并联合补充核黄素或／和烟酰胺和／或硫胺素组大鼠血清CHOL和LDL水平明显低于高脂对照组;而高脂喂养并联合补充烟酰胺（F3）及联合硫胺素（F5）或核黄素（F6）以及三者联合补充（F7）组大鼠LDL／HDL比值分别0．29、0．26、0．25和0．26,明显低于F0组的0．37（P值均小于0．05）。结论：大剂量烟酰胺可有效地调节血脂水平和控制肥胖大鼠的体重增长,而核黄素及硫胺素对控制肥胖     

组胺在哮喘豚鼠气道重塑中的作用

本研究旨在探讨组胺在哮喘豚鼠气道重塑中的作用。将50只健康雄性豚鼠随机分为5组。正常对照组：雾化吸入蒸馏水8周;哮喘模型组：致敏后雾化吸入卯白蛋白（ovalbumin,OVA）8周;哮喘模型延续组：致敏后雾化吸入OVA14周;组胺组：致敏后雾化吸入OVA14周,最后6周同时加用组胺：组胺受体拈抗剂组：致敏后雾化吸入OVA14周,最后6周同时加用组胺受体拈抗剂。检测血清组胺、Na^＋、Cl^-浓度、动脉血氧分压（PaO2）、动脉血二氧化碳分压（PaCO2）、pH、实际碳酸氢盐（actual bicarbonate,AB）、标准碳酸氧盐（standard bicarbonate,SB）以及气道壁粘膜层、基底膜层和平滑肌层厚度。所得结果如下：（1）哮喘模型组血清组胺浓度、气道擘厚度明显高于正常对照组（P〈0．01）;哮喘模型延续组明显高于哮喘模型组（P〈0.01）;组胺组明显高于哮喘模型延续组（P〈0．01）：组胺受体拮抗剂组低于哮喘模型延续组（P〈0．05,0．01）。（2）哮喘模型组PaO．小于正常对照组（P〈0．01）;哮喘模型延续组PaO2、pH、AB、SB小于哮喘模型组（P〈0．01）,而PaCO2大于哮喘模型组（P〈0．01）;组胺组PaO2、pH、AB、SB小于哮喘模型延续组（P〈0．01）,而PaCO2大于哮喘模型延续组（P〈0．01）;组胺受体拮抗剂组PaO2、pH、AB、SB高于哮喘模型延续组（P〈0．01）,而PaCO2低于哮喘模型延续组（P〈0．01）;血清Na^＋、Cl^-浓度各组间差异不明显。以上结果提示：（1）组胺在哮喘气道重塑中起介导作用。（2）应用组胺受体拈抗剂对防治哮喘气道重塑有一定作用。（3）PaO2、pH与气管、肺门支气管、肺外周小气道气道擘厚度呈负相关（P〈0．01）,而PaCO2、阴离子间隙（anion gap,AG）值与上述气道壁厚度呈止相关（P〈0．01）。     

A note on the failure of vitamin A to influence the epidermis of the brown trout, Salmo trutta L.

Three groups of hatchery–reared brown trout were fed for 32 weeks with synthetic diets containing 0, 18 and 100 i.u. vitamin A palmitate g⁻¹. Vitamin A levels in the liver of the fish at the end of the experiment were 3,50 and 300 i.u. g⁻¹ respectively. The growth rate was not significantly different between any of the three groups of fish. At all times during the investigation epidermal thickness andgoblet cell concentration were similar in the three groups but there were significant changes in goblet cell concentration within each group during the experimental period. Sexually mature males in all three groups offish contained significantly fewer epidermal goblet cells than immature fish of either sex.     

Artificial long days in addition to exogenous melatonin and daily contact with bucks stimulate the ovarian and oestrous activity in Mediterranean goat females

One experiment was conducted to determine whether the treatment with artificial long days and exogenous melatonin can induce reproductive activity during spring (seasonal anoestrus) in Mediterranean goats that are in daily contact with bucks and whether this treatment causes a variation in the reactivation of the reproductive activity in the normal breeding season. The experiment started on 4 November 2005 and finished on 27 October 2006. Thirty-four adult and barren does were used, distributed into two groups balanced according to their live weight (LW) and body condition score (BCS). Seventeen females were exposed to long days (16 h of light/day) from 14 November 2005 to 20 February 2006. On 20 February, they received one s.c. melatonin implant (LD-M group) and were exposed to natural photoperiodic changes in an open shed. The other females during the experiment were placed in an open shed under natural photoperiod and remained as the control group (C group). The C and LD-M groups were keeping in contact with males during the whole experiment. During the experiment, the LW, BCS and plasma progesterone concentrations were measured weekly, oestrous activity was tested daily using entire aproned bucks, and ovulation rate was evaluated by laparoscopy 7 days after positive identification of the oestrus. A clear treatment-time interaction was observed for plasma progesterone concentrations (P < 0.001), with a period of high progesterone concentrations during the natural seasonal anoestrus in the LD-M group. Although 94.1% of females in the LD-M group presented ovarian activity during this period, no female in group C did. Resumption of ovarian activity in the subsequent natural breeding season was 2 weeks later in the LD-M group in comparison with group C (P < 0.05). We can conclude that in Mediterranean goat breeding systems, when females are in daily contact with bucks, the treatment with 3 months of long days and melatonin implant at the end of the light photoperiodic treatment can induce ovarian and oestrous activity during the seasonal anoestrus. Finally, this treatment causes a short delay in the subsequent reactivation of ovarian activity in the natural breeding season.     

Effects of floor-feeding and the presence of a foraging substrate on the behaviour and stress physiological response of individually housed gilts

Both restricted feeding and barren housing have a negative influence on sow welfare. The aim of this study was to test whether sows that have to search for their feed in a substrate on the floor show less stereotyped (and other abnormal) behaviour and have a lower physiological stress response. In three batches, 96 gilts were housed individually in two rooms in 3.1 m² pens with 1.9 m² solid floor. In a 2×2 factorial design either wood shavings (S) or no substrate (NS) were provided on the floor, and 900 g of feed was provided twice daily (06:30 and 15:00 h) either in a trough (T) or on the floor (F). In weeks 8–12, behaviour was scan-sampled once in the periods 07:00–09:00 h (P1), 10:00–12:00 h (P2), and 13:00–15:00 h (P3). Data from the 5 weeks were pooled per animal. Video recordings (24 h) in week 12 or 13 were scan-sampled for ‘standing’. Saliva samples were taken in week 11 at 2 h intervals during 24 h and measured for cortisol. Spontaneously voided morning-urine was sampled in weeks 2, 7 and 12 or 13 for determination of ratios of adrenaline (A) and noradrenaline (NA) with creatinine (CR). Most effects that were found were due to substrate presence. Main findings were that compared with S-animals, NS-animals stood more during the dark period (4.8% versus 3.0%; P<0.05) and showed more (visible) oral behaviour in P1 (56.8% versus 47.6%; P<0.05), P2 (35.8% versus 30.8%; tendency) and P3 (44.1% versus 33.8%; P<0.05). This included more sham chewing in P1 (tendency), P2 and P3, more pen manipulation in P3, and more other oral behaviour (e.g. teeth grinding) in P1 (tendency) and P2. They had higher cortisol levels before feeding (peaks) and in the early evening (24 h average: 1.49 ng/ml versus 1.02 ng/ml; P<0.05) and higher NA/CR ratios in weeks 7 (tendency) and 12 (5.5 ng/mg versus 3.7 ng/mg; P<0.05). No treatment effects were found on A/CR ratios. Substantial interactive effects of feeding method and substrate were only found in floor manipulation. In all three periods NS-T-animals manipulated the floor less than other animals, probably because they had no attraction to the floor and were not rewarded for searching. Results imply that the presence of a substrate on the floor improves welfare, whereas provision of feed in the substrate in order to stimulate foraging behaviour is of less importance.     

Influence of individual predisposition, maternal experience and lactation environment on the responses of pigs to weaning at two different ages

This study assessed the effect of predisposition to perform harmful social behaviour, maternal rearing environment, and lactation environment on the responses of pigs to weaning at 3 or 5 weeks of age. Predisposed and non-predisposed gilts were selected as dams for this study at 7 weeks of age. Selection was based on behaviour in a “tail chew” test and performance of harmful social behaviour towards penmates. The gilts were mated at puberty with boars of a similar predisposition, and farrowed at approximately 44 weeks of age. Half of the gilts of each predisposition were reared from the time of selection until farrowing in barren environments, and half in enriched environments. During lactation, gilts and litters were either housed in a similar environment to that which gilts had experienced during rearing, or in a different environment (i.e. in terms of being barren or enriched). Litters from each treatment group were weaned at either 3 weeks of age (early weaning), or 5 weeks of age. After weaning, piglets were regrouped and housed in slatted pens without access to substrates. Non-predisposition to perform harmful social behaviour was associated with reduced growth during the post-weaning period (P < 0.01), and increased belly nosing behaviour in response to early weaning (P < 0.05). These effects were not mitigated by maternal experience or lactation environment factors, and it is concluded that this type of selection may not be commercially viable. Rearing dams in barren rather than enriched environments led to reduced welfare in offspring. This was reflected in increased adrenocortical reactivity during the lactation period (P < 0.01), and increased belly nosing behaviour in response to early weaning (P < 0.05). The effect of barren maternal rearing environments on belly nosing behaviour by offspring was eliminated when pigs were housed in enriched lactation environments (P < 0.01). Enrichment during the lactation period also led to improved growth rates in the post-weaning period (P < 0.01). It is suggested that this effect was due to an enhanced ability to cope with the weaning process. Overall, the results show that both genetic and early environmental factors are important determinants of the responses of pigs to weaning. Adverse effects of barren maternal rearing environments may be overcome by housing pigs in enriched lactation environments.     

压力性尿失禁动物模型尿道功能和盆底肌力的比较

目的:比较不同压力性尿失禁(stress urinary incontinence,SUI)动物模型在尿流动力学和盆底肌力方面的差异,以寻求最能模拟SUI的动物模型。方法:取64只大鼠随机均分为阴道扩张模型组(vaginal distension,VD)和阴部神经压榨模型组(pudendal nerve crush,PNC)和阴部神经切断模型组(pudendal nerve transection,PNT)以及VD+PNC造模组4组,每组16只,另取4只大鼠作为正常对照组。造模后第2天,所有大鼠行喷嚏试验。造模后第4天、第10天、3周、6周,测定尿流动力学和盆底肌力。正常对照组大鼠在喷嚏试验后进行尿流动力学和盆底肌力测定。结果:喷嚏实验结果显示正常对照组未观察到阳性大鼠(0/4),各模型组喷嚏试验结果阳性率均显著高于正常对照组(P0.05)。动力学检测显示:与正常组(40.3±3.4 cm H_2O)相比,VD组在造模后4d的LPP值显著降低(P0.05),而造模后10d、3周和6周时的LPP值无统计学差异(P0.05);PNC组和PNC+VD组在造模后4d、10d、3周时的LPP值均显著降低(P0.05),而在造模后6周时无统计学差异(P0.05);PNT组在造模后4d、10d、3周和6周时的LPP值均显著降低(P0.05)。最大膀胱容量测定显示:与正常组(2.42±0.12 mL)相比,VD组在造模后10d的MBC值显著降低(P0.05),而造模后4d、3周和6周时无统计学差异(P0.05);PNC组在造模后10d、3周时显著降低(P0.05),而在造模后4d和6周时无统计学差异(P0.05);PNC+VD组和PNT组在造模后10d及3周和6周时均显著降低(P0.05),而在造模后4d时无统计学差异(P0.05)。盆底肌力测定结果显示:与正常组的耻尾肌肌力值(2.71±0.12 g/g)相比,VD组在造模后10d显著降低(P0.05),而造模后4d、3周和6周时无统计学差异(P0.05);PNC组在造模后10d、3周时显著降低(P0.05),而在造模后4d和6周时无统计学差异(P0.05);PNC+VD组和PNT在造模后10d及3周和6周时均显著降低(P0.05),而在造模后4d时无统计学差异(P0.05)。结论:VD、PNC、VD+PNC和PNT造模均能有效模拟出SUI发病中的盆底神经和肌肉损伤。其中,VD造模主要引起盆底肌的直接损伤,但其恢复较快。PNC和PNT造模则能损伤阴部神经并间接地造成盆底肌的失神经性萎缩,但PNT所造成的损伤较难恢复,不能有效地模拟SUI的自然修复过程。而VD+PNC造模则兼具VD和PNC两种造模方法的特点,能从多个层面模拟SUI的发病。因此,在实践中应根据实验研究的层面采用合适的动物模型。     

Effect of supplemental dietary biotin on performance of lactating ewes

Seventy-two lactating Chios ewes were used in two experiments to determine effects of supplemental dietary biotin on productivity and milk composition. The first experiment started after weaning on day 42 postpartum, and lasted 20 weeks, while the second started on week 24 postpartum and lasted 12 weeks. In both experiments, ewes were allocated, after equal distribution relative to milk yield, body weight, time of lambing, and lactation number (i.e., two or three), into three groups of 24 ewes each, and were accommodated in three floor pens/groups of eight ewes/treatment. Ewes were fed one of three diets varying in supplemental biotin (BIOTIN0, no supplemental biotin; BIOTIN3, 3 mg supplemental biotin/ewe/day; BIOTIN5, 5 mg supplemental biotin/ewe/day) in each experiment. Milk, fat, protein, lactose and ash yield, and milk fat content increased linearly (P<0.012) with increased dietary biotin in both studies. Dietary biotin supplementation improved the productive performance of these lactating ewes at both an early and late stage of lactation.     

Does cyclicity of growth rate in rainbow trout exist?

Ninety rainbow trout Oncorhynchus mykiss were reared in three tanks ( n= 30), and their growth rate was monitored for 25 weeks. During the experiment, fish were fed ad libitum , and kept under simulated natural photoperiod and constant temperature (14 ± 1°C). Throughout the experiment, water quality (pH, O₂, N-NH₃, N-NH₄, NO₂) was considered optimum. Two growth rate periods were observed on the population: first an acclimation period (weeks 1–5), followed by a period of general decrease in growth rate (weeks 5–25). This trend was modelled with a third-order polynomial function. The autocorrelation analysis of the fluctuations revealed a cyclicity of the growth rate with a 4–5-week period. This cyclicity was independent of the tanks and of the growth rate trend type (long- v . short-term acclimation period). However, at the individual level, trends as well as short-term fluctuations were heterogeneous and no clear cyclicity could be detected. The biological relevance of the population growth rate cyclicity and the apparent absence of similar individual fluctuations are discussed.     

Long-term treatment with glibenclamide increases susceptibility of streptozotocin-induced diabetic rat heart to reperfusion-induced ventricular tachycardia

This study investigated the effects of long-term treatment with glibenclamide (GLIB) on the susceptibility of streptozotocin (STZ)-induced diabetic heart to ischemia/reperfusion insults. Starting 4 weeks after the injection of STZ, rats were treated with GLIB (0.1 mg/kg, ip, three times a week, STZ-GLIB group) or vehicle (STZ-VEH group) for 8 weeks. The recovery of cardiac performance, released creatine kinase (CK), and incidence of ventricular arrhythmias were studied during the reperfusion period in isolated hearts from rats in STZ-GLIB (n = 14) and in STZ-VEH groups (n = 13) and from age-matched control rats (CNT group, n = 14). Each heart was subjected to 5 min of global low-flow ischemia followed by 25 min of no-flow ischemia, with a subsequent 30 min of reperfusion. Plasma glucose level was not significantly different between the STZ-GLIB and STZ-VEH groups. The recovery of cardiac performance and the released CK during reperfusion period were significantly lower in both STZ-VEH and STZ-GLIB groups than in the CNT group (P < 0.01 and P < 0.05, respectively). Reperfusion resulted in an incidence of ventricular fibrillation in 23% and 21% in STZ-VEH and STZ-GLIB groups, respectively (P = ns). These values were significantly lower than that of the CNT group (100%, P < 0.001 for both). More importantly, the incidence of ventricular tachycardia in the STZ-GLIB group was significantly higher than that in the STZ-VEH group (93% vs 54%, P < 0.05) and was not significantly different from that in the CNT group (93% vs 100%, P = ns). The results suggest that STZ-induced protection against reperfusion-induced ventricular arrhythmias in diabetic heart may be partially abrogated by long-term treatment with GLIB.     

Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens

This study was conducted to evaluate the effect of early rearing conditions on physiological, haematological and immunological responses relevant to adaptation and long-term stress in white Leghorn hens with intact beaks housed in furnished cages (FC) or conventional cages (CC) during the laying period. Pullets were cage reared (CR) or litter floor reared (FR). From 16 to 76 weeks of age, hens were housed in FC (eight hens per cage) or in CC (three hens per cage). As measures of long-term stress at the end of the laying period, adrenal reactivity was quantified by assessing corticosterone responses to adrenocorticotropin challenge, and immune response was assessed by measuring antibody responses after immunization with sheep red blood cells (SRBC) and keyhole limpet haemocyanin (KLH). Heterophil to lymphocyte (H/L) ratio was employed as an indicator of stress. Rearing conditions significantly affected anti-SRBC titres (P < 0.0001) and tended to affect H/L ratios (P = 0.07), with the highest values found in FR hens. Layer housing affected H/L ratio (P < 0.01); the highest ratio was found in FR birds housed in FC during the laying period. This study shows that early rearing environment affects immunological indicators that are widely used to assess stress in laying hens. However, while results on H/L ratio indicated that FR birds experienced more stress particularly when they were housed in FC during the laying period, the immune responses to SRBC in FR hens was improved, indicating the opposite. This contradiction suggests that the effects on immune response may have been associated with pathogenic load due to environmental complexity in FR and FC hens rather than stress due to rearing system or housing system per se.     

Effect of starvation and refeeding on digestive enzyme activities in juvenile roach, Rutilus rutilus caspicus

We evaluated the effects of starvation and refeeding on digestive enzyme activities in juvenile roach, Rutilus rutilus caspicus. Fish were divided into four feeding groups (mean mass 1.68 ± 0.12 g). The control group was fed to satiation twice a day throughout the experiment with formulated diet (SFK). The other three groups were deprived of feed for 1(S1), 2(S2), and 3(S3) weeks, respectively, and then fed to satiation during the refeeding period. The results showed that trypsin specific activity was not affected significantly either by starvation or refeeding, in all experimental groups. Chymotrypsin specific activity did not change significantly in S1 fish during the experimental period. In S2 and S3 fish no significant changes were observed during the starvation period. Upon refeeding, the activity increased in S2 fish, while it decreased in S3 fish. Amylase specific activity decreased significantly during the starvation period in all experimental groups. Upon refeeding, the activity increased. Alkaline phosphatase specific activity did not change significantly during the experiment period in S3 fish, while it showed significant changes during the starvation and refeeding period in the S1 and S2 fish. Starvation also had a significant effect on the structure of the intestine.