成年小鼠颈5脊髓钳夹损伤模型的制备与评价

目的 :制备小鼠C5脊髓背侧及背外侧束钳夹损伤模型,评价损伤后动物的行为学和组织学表现。方法:采用C57/BL成年小鼠为实验对象,将16只动物随机分为损伤组和对照组,每组8只。动物麻醉后,切开背侧颈部皮肤,显露并切除小鼠C5椎板,损伤组采用自制改良FST DUMONT 5号手术钳分别钳夹背侧皮质脊髓束(dCST)和脊髓背外侧束两次;对照组仅切除椎板不做脊髓钳夹损伤。分别在术前和术后3d、2周、4周、6周、8周时采用圆筒实验、水平楼梯实验和食物抓取实验评价动物的行为学表现;术后8周时采用BDA顺行示踪观察皮质脊髓束(CST)和红核脊髓束(RST)在损伤后的情况。结果:钳夹损伤后,小鼠后肢步行功能正常但肢体的精细活动能力受到明显影响。在圆筒实验中,损伤组小鼠伤侧前肢的使用频率下降,前肢梳洗动作幅度受限,伤后各时间点与对照组相比差异均有统计学意义(P0.05);在水平楼梯实验中,损伤组小鼠对横梁的抓握精确性降低,伤后各时间点与对照组相比差异有统计学意义(P0.05);在食物抓取实验中,损伤组小鼠的食物抓取能力也出现了明显受限,伤后各时间点与对照组相比差异有统计学意义(P0.05)。以上行为学结果在伤后3d达高峰,2周后逐渐恢复,但直至8周仍不达正常水平。术后8周顺行示踪结果显示对照组小鼠CST和RST均显露清晰,纤维束呈纵行排列;损伤组小鼠CST和RST在损伤处大量断裂、逆向崩解,且无再生迹象。结论:成年小鼠C5脊髓钳夹损伤模型能够方便观察动物随意运动的控制情况及评价轴突的再生状况,适合作为轴突再生的研究模型。     

Balloon Retrograde Transvenous Obliteration Versus Endoscopic Cyanoacrylate in Bleeding Gastric Varices: Comparison of Rebleeding and Mortality with Extended Follow-up

Purpose

To assess short- and long-term mortality and rebleeding with endoscopic cyanoacrylate (EC) versus balloon-occluded retrograde transvenous obliteration (BRTO).

Employment Hardships and Single Mothers’ Self-Rated Health: Evidence from the Panel Study of Income Dynamics

Using a national sample of single mothers from the 2007 and 2009 waves of the Panel Study of Income Dynamics, this study examined the effects of multiple employment statuses on the selfrated health of single mothers during the recent economic recession. Unlike other studies, the current study minimized selection bias by controlling for prior self-rated health, in addition to other predisposing factors, enabling factors, and need factors. We found that underemployment, but not unemployment, is associated with lower levels of self-rated health of single mothers. Results further indicate that the 25–39 age range (compared to the 18–24 age range), lower family income, prior lower self-rated health, more chronic diseases, and binge drinking place single mothers at an increased risk of lower levels of self-rated health. In contrast, strength-building physical activity is significantly associated with higher levels of self-rated health. Implications for health care policy and social work practice are drawn from the results.     

基于无线刺激与遥测系统的心房颤动动物模型

目的探索一种可控、可靠、安全的心房颤动(简称房颤)动物模型的建立方法。方法自主设计并制作一种基于Microchip公司的PIC18(Peripheral Interface Controller,外围接口控制器)系列单片机和TI公司的RF(Radio Frequency,射频)无线收发芯片CC1101 CC1101(Chipcon公司)的植入式遥测刺激器,植入比格犬背部,记录电极留置腹侧皮下,刺激电极缝合于左心耳上,在犬清醒自由的条件下,通过计算机专用心电软件连续监测体表II导联心电信号,并发放间歇(刺激1 s,暂停2 s)高频(频率30 Hz)阈上(强度2 mA,脉宽5 ms)刺激,若间歇期内出现房颤,则人为干预中止刺激,若转为窦性心律,则继续刺激。结果植入式遥测刺激器在体外可稳定工作(包括采集模拟心电信号和发放刺激)30天,植入犬体内刺激3天后可诱导出房颤,持续时间最长达8 h。结论应用植入式遥测刺激器是建立房颤动物模型的可行性方法之一。     

Antibody repertoire development in fetal and neonatal piglets. XV. Porcine circovirus type 2 infection differentially affects serum IgG levels and antibodies to ORF2 in piglets free from other environmental factors

Porcine circovirus type 2 (PCV2) is an important pathogen in the porcine respiratory disease complex (PRDC) and its persistence may be due to dysregulation of systemic immunity. We examined this contention using isolator piglets. We present data on Ig levels in serum and bronchio-alveolar lavage (BAL), on antibody response to PCV2 and to TNP conjugates used as model antigens in 48 PCV2-infected isolator piglets. We compared these to data from TNP-immunized isolator piglets colonized with a probiotic flora, those infected with swine influenza (S-FLU) and those infected with porcine respiratory and reproductive syndrome virus (PRRSV). We found that PCV2 infection does not cause generalized hypergammaglobulinemia that characterizes PRRSV infections, but causes an unexplained increase in serum IgA. All animals had serum IgG to the ORF2 gene product of PCR2, but neither IgA nor IgG anti-ORF2 responses in BAL. PCV2 infection is a poor adjuvant since only natural anti-TNP antibodies were found. Unexpectedly, immunization appeared to result in lower Ig levels and lower anti-ORF2 responses. There was extreme variation in serum Ig levels in response to infection that could in part be traced to genetic and gender differences. These data suggest that non-replicating vaccines are unlikely to result in a significant primary antibody response but may prime the system for a secondary antibody and cytotoxic response following actual infection. In any case, developers may have to contend with significant genetic differences in the response of piglets to PCV2.     

The Effects on Transient Evoked Otoacoustic Emissions Following Changes in External Auditory Canal Acoustic Impedance

The form of the transient evoked otoacoustic emission (TEOAE) generated by an acoustic impulse and recorded in the external auditory canal is dependent on many factors. Of these, the acoustic impedance of the external canal is possibly the most important. The effect of a change of acoustic impedance on the TEOAEs, induced by filling the external canal with helium or sulphur hexafluoride gas, is measured in a group of normal hearing subjects. The fundamental frequency of the TEOAEs is found to depend upon the density of the gas in the external canal. Compared to that of air (density 1.29 g/1) the frequency increased with helium (density 0.178 g/1) and decreased with sulphur hexafluoride (density 6.6 g/1). The amplitude of the TEOAEs was also found to depend upon the density of the gas in the canal, decreasing with helium and increasing with sulphur hexafluoride. These results suggest that the TEOAEs observed in the group of subjects tested arose within the external auditory canal. This does not imply that cochlear emissions are not generated in response to transient acoustic impulses, rather it implies that this study failed to show the presence of a cochlear-mediated emission.