Electrical properties of neurons in the mediolateral part of the lateral septum: intracellular recordings from guinea-pig brain slices

Summary Membrane properties of 174 neurons were studied in the mediolateral part of the lateral septum (LSml) using an in vitro slice preparation of guinea-pig brain. Intracellular recordings were correlated with morphological data obtained from 34 neurons intracellularly stained with horseradish peroxidase (HRP). Neurons were divided into three classes according to their electrical responses. Class A and B neurons displayed the common property of an overshooting of spikes in response to the direct application of weak depolarizing current pulses. Class A neurons (59.2% of the total) generated tetrodotoxin-insensitive, high-threshold Ca²⁺ spikes in a control medium. Class B neurons (20.7% of the total) generated high-threshold Ca²⁺ spikes only if tetraethylammonium was used to block delayed rectifying K⁺ current. Features common to class A and B neurons included the inactivation of Na⁺ conductance, the participation of high-threshold Ca²⁺ conductance in the generation of spikes — when repetitive discharges were elicited by strong depolarizing current pulses — and Cs⁺sensitive, Ba²⁺-insensitive anomalous rectification. Class C neurons (20.1% of the total) displayed discharges comprising small-amplitude Na⁺ spikes followed by slow and large Ca²⁺ spikes, suggesting a locus of impalement which was not the soma. HRP-filled class B neurons (n = 5) were characterized by small to medium perikarya with spindly dendrites. The majority of HRP-filled class A (15/21) and all class C (n = 8) neurons showed large perikarya with thick primary dendrites and spiny dendritic branches. Thus, class A and C neurons typify the guinea-pig LSml in their morphological characteristics and in their ability to generate high-threshold Ca²⁺ spikes in a control medium.     

An in vitro preparation and study of cells in cat visual cortex

We have described full details of the preparation of slices from the visual cortex of cats. Then, we presented the results concerning the effects of the deprivation of glucose from the circulating medium on neuronal activities in the slices and the electrophysiological criteria for identifying glial cells in the sliced brain tissues. The results indicated that transsynaptic responses were reversibly blocked within 10-20 min, while nonsynaptic responses continued for more than 60 min in the glucose-free medium. We showed that glial cells could be identified according to the criteria proposed in in vivo experiments.     

receptors contribute to afferent synaptic transmission in the medial vestibular nucleus of young rats

In the medial vestibular nucleus (MVN), the (NMDA) subtype of ionotropic glutamate receptors has been reported as operating at synapses between ipsilateral vestibular afferents and neurons. In the present study, we addressed the question of whether or not NMDA receptors contribute to afferent synaptic transmission in the MVN and if so, to what degree. Using nystatin-perforated or conventional whole-cell patch clamp methods in brainstem slices of young rats (postnatal day 4–6), we found that NMDA receptors contribute to a substantial extent to afferent synaptic transmission in the MVN of young rats.     

Pharmacological characterization of excitatory synaptic potentials in rat basolateral amygdaloid neurons.

The pharmacological properties of synaptic responses in rat basolateral amygdaloid (BLA) neurons were studied using intracellular recording techniques. Three distinct types of synaptic potential were evoked by stimulation of the adjacent ventral endopyriform nucleus: 1) a fast excitatory postsynaptic potential (f-EPSP); 2) a late EPSP (1-EPSP) following the f-EPSP; and 3) a multiphasic hyperpolarization following the initial depolarizing potential. Superfusion of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a selective non-N-methyl-D-aspartate (non-NMDA) receptor antagonist, blocked the f-EPSP in a concentration-dependent manner. The ED50 for this effect was around 4 microM. In the presence of CNQX, however, a small depolarizing potential remained. This residual depolarizing component was markedly enhanced on removing Mg++ from the perfusing medium and could subsequently be abolished by DL-2-amino-5-phosphonovaleate (DL-APV, 50 microM) indicating its mediation via NMDA receptor-coupled ionophore. The l-EPSP was reversibly blocked by DL-APV. These results suggest that the pyriform cortex-amygdala pathway is mediated through excitatory amino acids acting on non-NMDA as well as NMDA receptors located on the BLA neurons.     

Ethanol exposure and withdrawal sensitizes the rat hippocampal CA1 pyramidal cell region to beta-amyloid (25-35)-induced cytotoxicity: NMDA receptor involvement

Abstract : Background: Millions of Americans suffer from Alzheimer's Disease (AD), which is characterized by significant neurological impairment and an accumulation in brain tissue of senile plaques consisting of beta amyloid (Aβ) peptide. The hippocampus, a region primarily responsible for learning and memory, appears to be particularly susceptible to AD‐related injury and chronic alcohol abuse. Although certain risk factors for AD are known, it is unclear if alcohol abuse or dependence may contribute to neuropathology in AD. Recent research suggests that low‐to‐moderate consumption of alcohol may protect against development of AD, while alcohol dependence may increase risk of developing AD. Therefore, the current studies aimed to investigate the effects of exposure to 50 or 100 mM ethanol (EtOH) and withdrawal on hippocampal injury induced by Aβ peptide treatment. Methods: The present studies exposed organotypic hippocampal slice cultures to 50 or 100 mM ethanol (EtOH) for 10 days, after which the slices underwent ethanol withdrawal (EWD) in the presence of varying concentrations of Aβ 25‐35 (0.1, 1, 10 μM), or 35‐25 (200 μM), a negative control reverse sequence peptide. Cellular injury, as evidenced by uptake of propidium iodide (PI), was assessed for each subregion of the hippocampal complex (CA1, CA3, and dentate gyrus). Results: Cellular injury in the CA1 pyramidal cell layer was significantly increased during withdrawal from exposure to 100 mM, but not 50 mM, EtOH. Exposure to Aβ in ethanol‐naïve cultures did not produce significant cytotoxicity. However, exposure to Aβ during EWD from 100 mM produced marked increases in CA1 pyramidal cell region cytotoxicity, effects reversed by cotreatment with a nontoxic concentration of the NMDA receptor channel blocker MK‐801 (20 μM). Conclusions: These data suggest that withdrawal from exposure to a high concentration of EtOH produces marked cellular injury in the hippocampus, particularly the CA1 subregion. Further, this EtOH exposure and withdrawal regimen sensitizes the hippocampus to the toxic effects of Aβ treatment in a manner reflecting over activity of NMDA receptor function.     

彩色角膜接触镜染色位置的调查研究

本研究通过100×,200×,400×显微镜,观察各种品牌的彩色角膜接触镜的纵断面切片,分析其染色材料的位置是否接触眼表结构,比较不同设计的彩色角膜接触镜可能对眼内造成的影响,为消费者的选择,质监部门及临床治疗提供实验以及理论依据。     

Clinical lymph node staging-Influence of slice thickness and reconstruction kernel on volumetry and RECIST measurements

Purpose

Therapy response evaluation in oncological patient care requires reproducible and accurate image evaluation. Today, common standard in measurement of tumour growth or shrinkage is one-dimensional RECIST 1.1. A proposed alternative method for therapy monitoring is computer aided volumetric analysis. In lung metastases volumetry proved high reliability and accuracy in experimental studies. High reliability and accuracy of volumetry in lung metastases has been proven. However, other metastatic lesions such as enlarged lymph nodes are far more challenging. The aim of this study was to investigate the reproducibility of semi-automated volumetric analysis of lymph node metastases as a function of both slice thickness and reconstruction kernel. In addition, manual long axis diameters (LAD) as well as short axis diameters (SAD) were compared to automated RECIST measurements.

Materials and methods

Multislice-CT of the chest, abdomen and pelvis of 15 patients with lymph node metastases of malignant melanoma were included. Raw data were reconstructed using different slice thicknesses (1–5 mm) and varying reconstruction kernels (B20f, B40f, B60f). Volume and RECIST measurements were performed for 85 lymph nodes between 10 and 60 mm using Oncology Prototype Software (Fraunhofer MEVIS, Siemens, Germany) and were compared to a defined reference volume and diameter by calculating absolute percentage errors (APE). Variability of the lymph node sizes was computed as relative measurement differences, precision of measurements was computed as relative measurement deviation.

Results

Mean absolute percentage error (APE) for volumetric analysis varied between 3.95% and 13.8% and increased significantly with slice thickness. Differences between reconstruction kernels were not significant, however, a trend towards middle soft tissue kernel could be observed.. Between automated and manual short axis diameter (SAD, RECIST 1.1) and long axis diameter (LAD, RECIST 1.0) no significant differences were found. The most unsatisfactory segmentation results occurred in higher slice thickness (3 and 5 mm) and sharp tissue kernel.

Conclusion

Volumetric analysis of lymph nodes works satisfying in a clinical setting. Thin slice reconstructions (≤3 mm) and a middle soft tissue reconstruction kernel are recommended. LAD and SAD did not show significant differences regarding APE. Automated RECIST measurement showed lower APE than manual measurement in trend.     

Exploring CBCT-Based DICOM Files. A Systematic Review on the Properties of Images Used to Evaluate Maxillofacial Bone Grafts

Previous studies suggests that cone beam computerized tomography (CBCT) images could provide reliable information regarding the fate of bone grafts in the maxillofacial region, but no systematic information regarding the standardization of CBCT settings and properties is available, i.e., there is a lack of information on how the images were generated, exported, and analyzed when bone grafts were evaluated. The aim of this study was to (1) do a systematic review on which type of CBCT-based DICOM images have been used for the evaluation of the fate of bone grafts in humans and (2) use a software suggested in the literature to test DICOM-based data sets, exemplifying the effect of variation in selected parameters (windowing/contrast control, plane definition, slice thickness, and number of measured slices) on the final image characteristics. The results from review identified three publications that used CBCT to evaluate maxillofacial bone grafts in humans, and in which the methodology/results comprised at least one of the expected outcomes (image acquisition protocol, image reconstruction, and image generation information). The experimental shows how the influence of information that was missing in the retrieved papers, can influence the reproducibility and the validity of image measurements. Although the use of CBCT-based images for the evaluation of bone grafts in humans has become more common, this does not reflect on a better standardization of the developed studies. Parameters regarding image acquisition and reconstruction, while important, are not addressed in the proper way in the literature, compromising the reproducibility and scientific impact of the studies.     

不同水模体直径和不同重建层厚对CT图像噪声的影响

目的 研究不同水模体直径和重建层厚等因素对CT图像噪声的影响,探讨CT质量控制检测中水模体合理的直径范围,为完善我国CT质量控制检测规范提供数据支持。方法 采用GE公司的Revolution型CT机,在两档剂量水平,即CTDI_W分别为30.20 mGy（120 kV、200 mAs）和49.82 mGy（120 kV、330 mAs）、图像重建层厚为5 mm和10 mm的条件下,分别对直径为16、18、20、22、24 cm的圆柱型均质水模体轴向扫描一圈,测量其CT值（水）和噪声等指标。比较不同水模体直径、不同层厚和不同剂量等条件下噪声测量值的差异。结果 噪声测量值随水模体直径增大而增大,随剂量增大而减小,在大小两档剂量水平下水模体直径分别为24、22 cm时的噪声值已超过现有检测标准;噪声随重建层厚的增大而减小。结论 噪声的测量结果与剂量、水模体直径、重建层厚等因素有关,在进行CT质量控制噪声项目的检测时,需规定所选择的剂量水平和层厚大小,并规定所选择水模体的直径大小。本研究结果提示CTDI_W在接近50 mGy的条件下,18~22 cm可能是比较合理的水模体直径范围。