Contributions of ion conductances to the onset responses of octopus cells in the ventral cochlear nucleus: simulation results

The onset response pattern displayed by octopus cells has been attributed to intrinsic membrane properties, low membrane impedance, and/or synaptic inputs. Although the importance of a low membrane impedance generally is acknowledged as an essential component, views differ on the role that ion channels play in producing the onset response. In this study, we use a computer model to investigate the contributions of ion channels to the responses of octopus cells. Simulations using current ramps indicate that, during the "ramp-up" stage, the membrane depolarizes, activating a low-threshold K(+) channel, K(LT), which increases membrane conductance and dynamically increases the current required to evoke an action potential. As a result, the model is sensitive to the rate that membrane potential changes when initiating an action potential. Results obtained when experimentally recorded spike trains of auditory-nerve fibers served as model inputs (simulating acoustic stimulation) demonstrate that a model with K(LT) conductance as the dominant conductance produces realistic onset response patterns. Systematically replacing the K(LT) conductance by a h-type conductance (which corresponds to a hyperpolarization-activated inward rectifier current, I(h)) or by a leakage conductance reduces the model's sensitivity to rate of change in membrane potential, and the model's response to "acoustic stimulation" becomes more chopper-like. Increasing the h-type conductance while maintaining a large K(LT) conductance causes an increase in threshold to both current steps and acoustic stimulation but does not significantly affect the model's sensitivity to rate of change in membrane potential and the onset response pattern under acoustic stimulation. These findings support the idea that K(LT), which is activated during depolarization, is the primary membrane conductance determining the response properties of octopus cells, and its dynamic role cannot be provided by a static membrane conductance. On the other hand, I(h), which is activated during hyperpolarization, does not play a large role in the basic onset response pattern but may regulate response threshold through its contribution to the membrane conductance.     

拟除虫菊酯浸泡大网孔门窗帘毒杀侵入实验小屋蚊虫的研究

本研究采用牛房实验小屋，加装不透光百叶窗和透光门廊，从而全面观察药帘对侵入实验小屋蚊虫毒杀情况，包括蚊虫入屋前接触药帘时和屋内蚊虫外逸出屋外后的死亡情况。结果表明，澳氰菊酯、二氯苯醚菊酯毒效强和持效长，浸泡门窗帘后６个月１８次试验，对侵入屋内蚊虫毒杀，平均死亡率分别为８９．４％和９０．６％。两药对入屋内蚊虫的吸血率均没有明显减少，可能与诱饵动物的吸引力有关。二氯苯醚菊酯有明显驱避作用，其减少蚊虫入屋率，按蚊为７０．６％，库蚊为７５．２％均没有明显减少，阿蚊却没有效应。     

The hypothalamus and the control of energy homeostasis: different circuits, different purposes.

The hypothalamus regulates many aspects of energy homeostasis, adjusting both the drive to eat and the expenditure of energy in response to a wide range of nutritional and other signals. It is becoming clear that various neural circuits operate to different degrees and probably serve specific functions under particular conditions of altered feeding behaviour. This review will discuss this functional diversity by illustrating hypothalamic neurones that express neuropeptide Y (NPY), the melanocortin-4 receptor (MC4-R) and the orexins. NPY neurones in the arcuate nucleus (ARC) release NPY, a powerful inducer of feeding and obesity, in the paraventricular nucleus (PVN) and the lateral hypothalamic area (LHA). ARC-NPY neurones are inhibited by leptin and insulin and become overactive when levels of these hormones fall during undernutrition. They may function physiologically to protect against starvation. With disruption of the inhibitory leptin signals due to gene mutations, the NPY neurones are overactive, which contributes to hyperphagia and obesity in the ob/ob and db/db mice and fa/fa Zucker rat. The MC4-R is activated by alpha-melanocyte-stimulating hormone [alpha-MSH; a cleavage product of pro-opiomelanocortin (POMC), which is expressed in the other ARC neurones] and inhibits feeding. This effect is antagonised by agouti gene-related peptide (AGRP), which is coexpressed by the ARC-NPY neurones only. Activation of MC4-R, possibly mediated by blockade of AGRP release, appears to restrain overeating of a palatable diet. This response may be programmed by a transient rise in leptin soon after presentation of palatable food, and rats that fail to do this will overeat and become obese. Orexin-A and -B (corresponding to hypocretins 1 and 2) are expressed in specific LHA neurones. These have extensive reciprocal connections with many areas involved in appetite control, including the nucleus of the solitary tracts (NTS), which relays vagal afferent satiety signals from the viscera. Orexin neurones also have close anatomical connections with LHA glucose-sensitive neurones. Orexin-A induces acute feeding but does not cause obesity. Orexin neurones are stimulated by hypoglycaemia partly via the NTS and inhibited by food ingestion. These neurones may therefore be involved in the severe hyperphagia of hypoglycaemia and short-term control of feeding.     

Evaluation of endothelial cell migration with a novel in vitro assay system

In this study we introduce a novel in vitro 'oil-drop' assay system for the measurement of endothelial cell (EC) migration, based on the original concept of the Teflon fence assay (Pratt et al., 1984; Am. J. Pathol. 117: 349–354). An aliquot of 15–20,000 human umbilical vein EC (HUVEC) is pipetted through a layer of mineral oil. The cells readily attach, spread and migrate on the surface of a matrix-coated tissue culture dish as a confluent circular monolayer. Migration is measured as the net increase in the total area covered at 24 hours. We have used this system to quantify EC migration on matrices composed of a mixture of type I collagen and either von Willebrand factor (vWF) or fibronectin (FN) in the presence or absence of tumor necrosis factor (TNF). Plating efficiency on both vWF/collagen and FN/collagen, measured by counting cells after attachment and spreading, is about 80%. With this method, migration on vWF/collagen was about 6.4 mm² and 5.3 mm² for TNF-treated and untreated HUVEC, respectively. HUVEC migration on FN/collagen was slightly greater – 6.4 mm² and 6.5 mm² with and without TNF treatment, respectively. During the 24 hour time period, HUVEC numbers increased 30–40% on vWF/collagen, and 60–80% on FN/collagen, with increased proliferation observed with TNF- treatment. EC proliferation could be completely inhibited by 2 mM hydroxyurea. This assay system has proven useful in our studies to quantify cell migration and proliferation.     

Polysaccharide-protein surface modification of titanium via a layer-by-layer technique: characterization and cell behaviour aspects

To improve the surface biocompatibility of titanium films, a layer-by-layer (LBL) self-assembly technique, based on the polyelectrolyte-mediated electrostatic adsorption of chitosan (Chi) and gelatin (Gel), was used leading to the formation of multilayers on the titanium thin film surfaces. The film growth was initialized by deposition of one layer of positively charged poly(ethylene imine) (PEI). Then the thin film was formed by the alternate deposition of negatively charged Gel and positively charged Chi utilizing electrostatic interactions. The LBL film growth was monitored by several techniques. The chemical composition, surface topography as well as wettability were investigated by using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM) and water contact angle measurement, respectively. Quantitative XPS analysis showed the alternative change of C/N ratio after four sequential cycles coating of Ti/PEI/Gel/Chi/Gel, which indicated the discrete layer structure of coatings. Uncoated titanium (control sample) displayed a smooth surface morphology (root mean square (RMS) roughness was around 2.5 nm). A full coverage of coating with Gel/Chi layers was achieved on the titanium surface only after the deposition layers of PEI/(Gel/Chi)2. The PEI/Gel/(Chi/Gel)3 layer displayed a rough surface morphology with a tree-like structure (RMS roughness is around 82 nm). These results showed that titanium films could be modified with Chi/Gel which may affect the biocompatibility of the modified titanium films. To confirm this hypothesis, cell proliferation and cell viability of osteoblasts on LBL-modified titanium films as well as control samples were investigated in vitro. The proliferation of osteoblasts on modified titanium films was found to be greater than that on control (p<0.05) after 1 and 7 days culture, respectively. Cell viability measurement showed that the Chi/Gel-modified films have higher cell viability (p<0.05) than the control. These data suggest that Chi/Gel were successfully employed to surface engineer titanium via LBL technique, and enhanced its cell biocompatibility. The approach presented here may be exploited for fabrication of titanium-based implant surfaces.     

不同来源的TIL临床应用研究

以５１例晚期肿瘤患者作为研究对象，对其不同来源的肿瘤浸润淋巴细胞（ＴＩＬ）进行治疗研究，发现肿瘤组织来源的ＴＩＬ其有效率及一年生存率明显高于胸腹水及转移淋巴结的ＴＡＬ；其中肿瘤组织的ＴＩＬ，胸腹水、转移淋巴结的ＴＡＬ有效率分别为８０．９％、４０．０％、４６．６％；三者治疗肿瘤患者的一年生存率分别为８１．０％、４６．７％、６０．０％；另外发现胸腹水ＴＡＬ对实质性肿块治疗疗效较低，为４０％，其中静脉滴     

人表皮郎格罕细胞Birbeck颗粒的超微结构观察

本文对正常人表皮郎格罕细胞MBirbeck颗粒(LG)怍了超微结构观察。计数十个细胞中146个LG的各种切面形态和出现频率,结果为:杆状占53.4％,球拍状占8.2％,泡状占7.5％,弧状占15％,环状占11％,同号状占4.8％六种。LG长约100-500nm,杆部宽为40-50nm,泡直径为70-350nm,环状的环厚为25-50am。本结果提示LG的本体结构除扁盘状和扁盘泡状外,还可能存在扁盘杯状的立体模式。     

Three‐Dimensional Reconstruction of the Optic Canal‐Based on Multislice Helical CT: A Comparison Analysis with Skull Dissection of 40 Postmortem Cases

Decompression operation of the optic canal via the nasal path under endoscope is widely used, but it is both a challenging and controversial method. Unsatisfactory results were largely associated with otolaryngologists' limited understanding of the real anatomical situations of the optic canal before operation. To provide otolaryngologists with the real situations and data preoperation, multislice helical CT was used to reconstruct the images of the optic canal. Using multislice helical CT‐aided three‐dimensional reconstructive methods in combination with direct anatomic measurement, we dissected and analyzed the shape of the optic canal and its anatomic relationship with the adjoining structures in 40 intact postmortem skull samples. The In‐Space technique clearly showed the structure and the related region of the optic canal. The virtual endoscopy technique showed superbly the spatial appearance and topography of the inner optic canal and also gave the inner structure of the optic canal optically. There was no statistic difference in three‐dimensional reconstructive data with that obtained by anatomical measurements and thus can be used to directly instruct the clinic operation. These results demonstrate that a combined In‐Space technique with virtual endoscopy can accurately define the subtle structure and the related region of the optical canal. In conclusion, multislice helical CT‐based three‐dimensional reconstruction is of important value for clinical operations. Anat Rec, 2008. © 2008 Wiley‐Liss, Inc.     

大鼠肺微血管内皮细胞培养及其粘弹性研究

为了建立肺微血管内皮细胞培养方法 ,研究肺微血管内皮细胞粘弹性。我们取大鼠肺周边组织 (宽度不应大于 1.5 mm) ,将组织剪成 1.5 mm× 1mm× 1mm的组织块 ,贴入无菌的 2 5 cm3培养瓶 ,每瓶 10～ 15块 ,同时加入含 2 0胎牛血清、肝素 90 U/ml、L-谷氨酰胺 4mmol、青霉素 10 0 U/ml和链霉素 10 0 μg/ml的 DMEM培养基 3ml,放入 37℃二氧化碳培养箱中静置培养 ;8h后翻转培养瓶 ,6 0 h后取出肺组织块 ,接着继续培养 2～ 4d后进行传代。最后消化分离肺微血管内皮细胞 ,用微管吸吮系统研究肺微血管内皮细胞粘弹性。结果显示 :肺微血管内皮细胞通过倒置相差显微镜观察 ,细胞呈鹅卵石镶嵌状排列 ,状如梭形或多角形 ,大小均匀 ,胞核清晰 ,呈卵圆形 ,胞浆丰富 ; 因子相关抗原免疫荧光染色呈阳性 ;肺微血管内皮细胞弹性模量 K1 =49.3± 9.2 Pa、K2 =73.2±2 4.8Pa、粘性系数 μ=19.2± 7.2 Pa.s。这些结果表明用组织块法培养肺微血管内皮细胞是可行的 ,肺微血管内皮细胞表现出较大的刚性