Glucocorticoid enhancement of memory consolidation in the rat is blocked by muscarinic receptor antagonism in the basolateral amygdala

Glucocorticoid-induced memory enhancement is known to depend on beta-adrenoceptor activation in the basolateral amygdala (BLA). Additionally, inactivation of muscarinic cholinergic receptors in the rat amygdala blocks memory enhancement induced by concurrent beta-adrenergic activation. Together, these findings suggest that glucocorticoid-induced modulation of memory consolidation requires cholinergic as well as adrenergic activation in the BLA. Two experiments investigated this issue. The first experiment examined whether blockade of muscarinic cholinergic receptors in the BLA with atropine alters the memory-enhancing effects of the systemically administered glucocorticoid dexamethasone. Dexamethasone (0.3, 1.0 or 3.0 mg/kg, s.c.) administered to rats immediately after inhibitory avoidance training produced dose-dependent enhancement of 48-h retention. Concurrent bilateral infusions of the muscarinic cholinergic antagonist atropine (0.5 microg in 0.2 microL per side) into the BLA blocked the memory enhancement. The second experiment investigated whether the BLA is a locus of interaction between glucocorticoid and muscarinic activation. The specific glucocorticoid receptor (GR or type II) agonist RU 28362 (1.0, 3.0 or 10 ng) was infused into the BLA either alone or together with atropine immediately after training. The GR agonist produced dose-dependent memory enhancement and atropine blocked the memory enhancement. These findings indicate that muscarinic cholinergic activation within the BLA is critical for enabling glucocorticoid enhancement of memory consolidation and that enhancement of memory induced by GR activation in the BLA requires cholinergic activation within the BLA.     

Cardioprotective effects of saponins from Panax japonicus on acute myocardial ischemia against oxidative stress-triggered damage and cardiac cell death in rats

Aim

To study the cardioprotective effects of saponins from Panax japonicus (SPJ) on acute myocardial ischemia injury rats induced by ligating of the left anterior descending branch (LAD), on the basis of this investigation, the possible mechanism of SPJ was elucidated.

Materials and methods

SPJ was identified by high performance liquid chromatography-evaporative light scattering detection. Male Sprague-Dawley rats (200–220 g) were randomly divided into four groups: sham-operated, LAD, LAD + l-SPJ (SPJ, 50 mg/kg/day, orally) and LAD + h-SPJ (SPJ, 100 mg/kg/day, orally). Before operation, the foregoing groups were pretreated with homologous drug once a day for 7 days, respectively. After twelve hours in LAD, the cardioprotective effects of SPJ were evaluated by infarct size, biochemical values, hemodynamic, and histopathological observations and the antioxidative and antiapoptotic relative gene expressions.

Results

SPJ significantly improved heart function and decreased infarct size; remarkably decreased levels of serum lactate dehydrogenase, creatine kinase, xanthine oxide and malondialdehyde content, increased contents of serum total antioxidant capacity, superoxide dismutase (SOD), glutathione peroxidase, catalase; quantitative real-time PCR results showed that SPJ might markedly reverse the down-regulated mRNA expressions of the SOD1, SOD2 and SOD3, ameliorate the increased Bax and caspase-3 mRNA expressions and decreased Bcl-2 mRNA expression and ratios of Bcl-2 to Bax. Histopathological observations provided supportive evidence for biochemical analyses, and with the dose of SPJ increasing, the aforesaid improvement became more and more strong.

Conclusions

The studies demonstrated that in ischemic myocardium, oxidative stress caused the overgeneration and accumulation of reactive oxygen species (ROS), which was central of cardiac ischemic injury. SPJ exerted beneficially cardioprotective effects on myocardial ischemia injury rats, mainly scavenging oxidative stress-triggered overgeneration and accumulation of ROS, alleviating myocardial ischemia injury and cardiac cell death.     

Loss of dystrophin staining in cardiomyocytes: a novel method for detection early myocardial infarction

Myocardial infarction (MI) is the most frequent diagnosis made in majority of sudden death cases subjected to clinical and medicolegal autopsies. When sudden death occurs at a very early stage of MI, traditional macroscopic examination, or histological stains cannot easily detect the myocardial changes. For this reason we propose a new method for detecting MI at an early stage. Murine model of MI was used to induce MI through permanent ligation of left anterior descending branch of left coronary artery. Five groups of C57B6/J mice were used for inducing MI, which includes 20 minutes, 30 minutes, one hour, four hours and 24 hours post MI groups. One naïve group and sham-operated groups were used as controls. There is loss of dystrophin membranous staining in cardiac myocytes occurs as early as 20 minutes post myocardial infarction. This can be used as a novel method to diagnose early myocardial infarction in post mortem cases where diagnosis is unclear. In conclusion, evaluation of immunohistochemical expression of dystrophin represents a highly sensitive method for detecting early myocardial infarction due to the loss of staining in the infarcted areas. Dystrophin immunostaining can also be used to assess myocardial architecture.     

Exploitation of natural geometrical regularities facilitates target detection

We have evolved to operate within a dynamic visual world in which natural visual signals are not random but have various statistical regularities. Our rich experience of the probability structure of these regularities could influence visual computation. Considering that spatiotemporal regularity, co-linearity and co-circularity are common geometrical regularities in natural scenes, we explored how our visual system exploits these regularities to achieve accurate and efficient representations of the external world. By measuring human contrast detection performance of a briefly presented foveal target embedded in dynamic stimulus sequences (comprising six short bars appearing consecutively towards the fovea) imitating common regularity structures, we found that both contrast sensitivity and reaction time for target detection was facilitated by predictable spatiotemporal stimulus structure. Qualitatively consistent with natural image analysis that co-linearity is a stronger statistical feature than co-circularity, the facilitation in target detection was more evident for predictable stimulus sequences following a co-linear path than a co-circular path. Control experiments further showed that response bias and uncertainty reduction could not fully account for our observation. It seems that our visual system exploits geometrical natural regularities to facilitate the interpretation of incoming visual signals, such as constraining interpretation on the basis of contextual priors.     

Envelope Coding in Auditory Nerve Fibers Following Noise-Induced Hearing Loss

Recent perceptual studies suggest that listeners with sensorineural hearing loss (SNHL) have a reduced ability to use temporal fine-structure cues, whereas the effects of SNHL on temporal envelope cues are generally thought to be minimal. Several perceptual studies suggest that envelope coding may actually be enhanced following SNHL and that this effect may actually degrade listening in modulated maskers (e.g., competing talkers). The present study examined physiological effects of SNHL on envelope coding in auditory nerve (AN) fibers in relation to fine-structure coding. Responses were compared between anesthetized chinchillas with normal hearing and those with a mild–moderate noise-induced hearing loss. Temporal envelope coding of narrowband-modulated stimuli (sinusoidally amplitude-modulated tones and single-formant stimuli) was quantified with several neural metrics. The relative strength of envelope and fine-structure coding was compared using shuffled correlogram analyses. On average, the strength of envelope coding was enhanced in noise-exposed AN fibers. A high degree of enhanced envelope coding was observed in AN fibers with high thresholds and very steep rate-level functions, which were likely associated with severe outer and inner hair cell damage. Degradation in fine-structure coding was observed in that the transition between AN fibers coding primarily fine structure or envelope occurred at lower characteristic frequencies following SNHL. This relative fine-structure degradation occurred despite no degradation in the fundamental ability of AN fibers to encode fine structure and did not depend on reduced frequency selectivity. Overall, these data suggest the need to consider the relative effects of SNHL on envelope and fine-structure coding in evaluating perceptual deficits in temporal processing of complex stimuli.     

Symmetry detection in typically and atypically speech lateralized individuals: A visual half-field study

Visuospatial functions are typically lateralized to the right cerebral hemisphere, giving rise to a left visual field advantage in visual half-field tasks. In a first study we investigated whether this is also true for symmetry detection off fixation. Twenty right-handed participants with left hemisphere speech dominance took part in a visual half-field experiment requiring them to judge the symmetry of 2-dimensional figures made by joining rectangles in symmetrical or asymmetrical ways. As expected, a significant left visual field advantage was observed for the symmetrical figures. In a second study, we replicated the study with 37 left-handed participants and left hemisphere speech dominance. We again found a left visual field advantage. Finally, in a third study, we included 17 participants with known right hemisphere dominance for speech (speech dominance had been identified with fMRI in an earlier study; Van der Haegen, Cai, Seurinck, & Brysbaert, 2011). Around half of these individuals showed a reversed pattern, i.e. a right visual half-field advantage for symmetric figures while the other half replicated the left visual-field advantage. These findings suggest that symmetry detection is indeed a cognitive function lateralized to the right hemisphere for the majority of the population. The data of the participants with atypical speech dominance are more in line with the idea that language and visuospatial functions are lateralized in opposite brain hemispheres than with the idea that different functions lateralize independently, although there seems to be more variability in this group.     

AKT、ATM、D4-GDI和p53 4条细胞凋亡通路基因在大鼠肝再生过程中的表达变化

目的探讨AKT、ATM、D4-GDI和p53 4条细胞凋亡通路基因在肝再生(LR)过程中的表达变化。方法将大鼠随机分为实验组和对照组,每组6只,雌雄各半,用Rat Genome 230 2.0芯片检测大鼠部分肝切除(PH)后不同恢复时间点4条细胞凋亡通路基因表达情况,并用生物信息学方法对其进行分析。结果 AKT、ATM、D4-GDI和p53 4条细胞凋亡通路中63、8、6和7个基因与肝再生相关。它们主要在肝再生启动阶段起始表达。表达的相似性分为均上调、上调占优势、均下调、下调占优势、上调和下调相近等5类,大多数基因表达加强,少数基因表达降低。它们表达的时间相关性分为11组。基因协同作用模型(Et)分析表明,AKT通路几乎在整个肝再生中抑制细胞凋亡;ATM、D4-GDI和p53 3条细胞凋亡通路几乎在整个肝再生中促进细胞凋亡。结论 AKT、ATM、D4-GDI和p53 4条细胞凋亡通路与再生肝生长、发育和肝量控制密切相关。     

检测水发或水产品中甲醛的快速定性检测试纸的实验研究与应用

[目的]研究快速有效地鉴定水产品、水发制品是否人为添加甲醛的方法。[方法]2003年,研制水产品或水发产品中甲醛的定性快速检测试纸,进行试纸检测灵敏度和抗干扰分析,并与我国卫生部在2001年推荐的乙酰丙酮分光光度法同时进行样品检测。[结果]试纸检测甲醛下限1×10-3mol/L(30×10-6kg/L);试纸检测甲醛时间不超过3min;试纸检测甲醛具有抗干扰性。[结论]本发明试纸已于2005年取得中国发明专利(专利号:ZL 03 1 78350.3)。     

B 超联合心电图诊断高血压性心脏病的临床研究

目的:探讨B超联合心电图诊断高血压性心脏病的临床效果及其应用价值. 方法:选取2014年6月至2014年11月我院收治的90例高血压性心脏病患者,对其临床资料进行回顾性分析,对比分析B超联合心电图及单独采用B超及心电图的诊断效果. 结果:以B超联合心电图诊断组患者的左室肥厚诊断准确率(66.67%)明显高于单独采用B超诊断组患者准确率(60.00%)及单独采用心电图诊断组患者准确率(40.00%) ,且差异具有统计学意义( P<0.05). 结论:以B超联合心电图的方式作为诊断高血压性心脏病的诊断方法较单独采用B超或心电图的诊断方式,其效果更为显著,准确性更高,具有广泛的临床使用价值.