Carbon monoxide and skate gastric cells: respiration and action spectrum

The rate of O₂ uptake in cells isolated from the skate gastric mucosa was determined as a function of the ratio [CO]/[O₂] by an O₂ electrode method. Skate cells are five times less sensitive to the effects of CO than yeast, which was used as a normal control cell. In both cell types, CO inhibition can be partially reversed by white light. Therefore, the action spectrum for the relief of CO inhibition was determined for the two cell types. In yeast, the alpha peak of the action spectrum for photodissociation of the CO-oxidase complex (which is the alpha peak of the absorption spectrum of this complex) is found at 590 nm, as expected from prior work on this oxidase. In skate gastric mucosa cells, the corresponding peak is at 580 nm, and these two peaks clearly represent different CO complexes. These observations help to explain the lack of CO inhibition of acid secretion in the skate gastric mucosa, and the observation of a non-standard terminal oxidase in the absorption spectrum of this tissue.Abbreviations DNP 2, 4-dinitrophenol - Kl_M Michaelis constant - ACD analog to digital converter - K _i dissociation coefficient for enzyme-inhibitor complex     

Ultrastructural diversity in motor units of crustacean stomach muscles

The physiological and ultrastructural properties of muscle fiber.s comprising three motor units in the gastric mill of blue crabs are described. In their contractile properties muscle fibers in all motor units are similar and resemble the slow type fibers in crustacean limb muscles. The majority of fibers generate large excitatory post-synaptic potentials which do not facilitate strongly. Structurally two types of fibers are found. The one type has long sarcomeres (greater than 6 mum), thin to thick myofilament ratios of 5-6:1 and diads located near the ends of the A-band. The other type has shorter sarcomeres (less than 6 mum), thin to thick myofilament ratios of 3:1 and diads located at mid sarcomere level. Both types of fibers occur within a single motor unit and this differs from the vertebrate situation. Furthermore, the finding of fibers with a low thin to thick myofilament ratio of 3:1 demonstrates that they are not exclusive to fast type crustacean muscle but also occur in slow stomach muscles.     

ATP/ADP exchange activity of gastric (H+ + K+)-ATPase

The ATP/ADP exchange is shown to be a partial reaction of the $\text{(}\text{H}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ by the absence of measurable nucleoside diphosphokinase activity and the insensitivity of the reaction to $\text{P}{}^1$, $\text{P}{}^5$ -di(adenosine-5′) pentaphosphate, a myokinase inhibitor. The exchange demonstrates an absolute requirement for Mg²⁺ and is optimal at an ADP/ATP ratio of 2. The high ATP concentration ($\text{K}{}_{0.5}\text{= 116 μ}\text{M}$) required for maximal exchange is interpreted as evidence for the involvement of a low affinity form of nucleotide site. The ATP/ADP exchange is regarded as evidence for an ADP-sensitive form of the phosphoenzyme. In native enzyme, pre-steady state kinetics show that the formation of the phosphoenzyme is partially sensitive to ADP while modification of the enzyme by pretreatment with 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) in the absence of Mg²⁺ results in a steady-state phosphoenzyme population, a component of which is ADP sensitive. The ATP/ADP exchange reaction can be either stimulated or inhibited by the presence of K⁺ as a function of pH and Mg²⁺.     

Involvement of ryanodine receptors in pacemaker Ca2+ oscillation in murine gastric ICC

Using a cell cluster preparation from the stomach smooth muscle tissue of mice, we measured intracellular Ca(2+) oscillations in interstitial cells of Cajal (ICCs) in the presence of nifedipine. Pacemaker [Ca(2+)](i) activity in ICCs was significantly suppressed by caffeine application and restored after washout. Application of either ryanodine or FK-506 terminated the pacemaker [Ca(2+)](i) activity irreversibly. Immunostaining of smooth muscle tissue showed that c-Kit-immunopositive cells (that form network-like structure cells in the myenteric plexus, equivalent to ICCs) clearly express ryanodine receptors (RyR). RT-PCR revealed that ICCs (identified with c-Kit-immunoreactivity) predominantly express type 3 RyR (RyR3). Furthermore, the FK-binding proteins 12 and 12.6, both of which would interact with RyR3, were detected. In conclusion, we provide first evidence for the essential contribution of RyR to generating pacemaker activity in gastric motility. Similar mechanisms might account for spontaneous rhythmicity seen in smooth muscle tissues distributed in the autonomic nervous system.     

菌群失调腹泻抗生素造模对小鼠肠黏膜的影响

目的研究抗生素造模对菌群失调腹泻小鼠肠黏膜的影响。方法正常组给予无菌生理盐水0.35m L/(只·次)灌胃,其余各组采用头孢拉定胶囊和硫酸庆大霉素注射液用无菌生理盐水配成浓度为62.5g/L抗生素混合液0.35 m L/(只·次)灌胃。每天2次,连续5 d。造模成功后,采集小鼠空肠、回肠和结肠,分别测量绒毛高度、隐窝深度、淋巴细胞数和肠黏膜厚度,观察肠黏膜情况。结果菌群失调腹泻抗生素造模后,空肠、回肠和结肠的隐窝深度及肠黏膜厚度与正常组相比,差异无统计学意义(P0.05);造模后的结肠淋巴细胞数与正常组相比较,高于正常组,差异有统计学意义(P0.05),造模后的空肠绒毛高度与正常组相比,明显低于正常组,差异有统计学意义(P0.01)。结论菌群失调腹泻抗生素造模使结肠淋巴细胞数增高,空肠绒毛高度降低。     

胃癌患者血清IL-17、IL-6和TGF-β1水平及其临床意义

目的:探讨胃癌患者外周血中白介素17(IL-17)、白介素6(IL-6)和转化生长因子-β1(TGF-β1)的表达水平及其临床意义。方法:选择2009年1月~2010年1月我院收治的50例胃癌患者(观察组)及同期50例健康对照者(对照组)为研究对象,采用ELISA法检测和比较其外周血中IL-17、IL-6和TGF-β1的水平,并分析胃癌患者外周血中IL-17、IL-6和TGF-β1水平与其临床病理特征之间的相关性。结果:观察组患者外周血中IL-17、IL-6和TGF-β1的水平分别为(8.51±2.68)pg/ml、(7.81±5.41)pg/ml和(1093.42±831.21)pg/ml,均明显高于健康对照组(P0.01)。胃癌患者的血清IL-17、TGF-β1的水平与其年龄、性别、临床分期、有无淋巴结转移、分化程度、肿瘤部位及大小均无明显相关性(P0.05);而血清IL-6的水平与肿瘤的大小相关(P0.05),但与其他临床病理特征无关(P0.05);血清IL-17水平与IL-6、TGF-β1的水平均无明显相关性(P0.05)。结论:血清IL-17、IL-6和TGF-β1水平的升高与胃癌的发生有关,但IL-6和TGF-β1可能不是血清中IL-17生成的诱导因子。     

胃转流术后远端肠黏膜形态及生长因子表达的变化

目的:探讨胃转流术后远端肠管黏膜的适应性变化及生长因子的表达情况。方法:将8周龄的Wistar大鼠随机分为对照组、假手术组和胃转流术组,术后8周取吻合口远端肠管行常规病理切片检查,测量肠黏膜厚度和绒毛高度,采用免疫荧光法检测肠粘膜中表皮生长因子(EGF)和胰岛素样生长因子-1(IGF-1)的表达。结果:胃转流术组黏膜厚度(672±39与500±31μm,P<0.01)和绒毛高度(445±19与342±15μm,P<0.01)均显著高于假手术组(P<0.01),而对照组和假手术组间均无显著差异。与假手术组比较,胃转流术组肠粘膜中EGF和IGF-1的表达显著升高(P<0.01),而对照组和假手术组间无显著差异。结论:胃转流术后远端肠管粘膜发生适应性增生,同时伴随着EGF和IGF-1表达水平的升高。