Association between increase in cyclic AMP and subsequent induction of tyrosine hydroxylase in rat adrenal medulla

Summary After male rats (100 g body weight) have completed 7 min of swimming at 15°C, their rectal temperature is decreased by 15°C. As expected, the increase of cAMP and the decrease of cGMP concentrations in adrenal medulla are delayed by the time period necessary for the body temperature to return to normal. Thus, taking into consideration the delaying effect of hypothermia, the swimming stress experiments are in agreement with the view that the enhancement of cyclic AMP/cGMP concentration ratios may function as the second messengers for the induction of tyrosine hydroxylase in adrenal medulla.     

High magnitude cyclic load triggers inflammatory response in lumbar ligaments

Background

Cumulative trauma disorder is commonly reported by workers engaged in prolonged repetitive/cyclic occupational activities. Recent experimental evidence confirms that relatively short periods of cyclic lumbar flexion at high loads result in substantial creep of viscoelastic tissues, prolonged periods of its recovery to baseline together with a neuromuscular disorder and exposure to instability. The biochemical process associated with the creep and neuromuscular disorder are not well explored. The purpose of the study is to identify the ligaments as one of the organs of failure and an acute inflammation as the result of failure as a preliminary step in the development of chronic inflammation that might lead to cumulative trauma disorder elicited by high magnitude cyclic loads.

Methods

The lumbar spine of anaesthetized cats was subjected to cyclic flexion loading at high magnitudes for six periods of 10 min each with 10 min rest in between followed by 7 h rest. Lumbar displacement was monitored throughout. Supraspinous ligaments from L-3/4, L-4/5, L-5/6 and unloaded T-10/11 were removed at the end of testing and assessed using mRNA expression for cytokine (IL-1β, IL-6, IL-8, TNFα, TGFβ). Cytokines expression in the lumbar ligaments were statistically compared to their self control in the unloaded thoracic ligament. The creep developed during the loading and its recovery during the 7 h rest was calculated.

Findings

The mean creep developed during the loading period reached 57.3% recovering to a residual value of 25.5% at the end of the 7 h rest. Increase in cytokine expression was seen in all lumbar ligaments with statistical significance in the L-4/5 and L-5/6 levels.

Interpretation

The results confirm that prolonged high magnitude cyclic loading of the lumbar spine in flexion–extension elicits substantial residual creep together with significant increases in cytokines expression, consistent with an acute inflammation, several hours post loading. Further exposure to cyclic loading over time may result in conversion to chronic inflammation.     

Bakuchicin induces vascular relaxation via endothelium-dependent NO-cGMP signaling

Bakuchicin is a furanocoumarin derived from the seeds of Psoralea corylifolia. The aim of the present study was to investigate the effect of bakuchicin on vascular tone in rat aortic tissue. Bakuchicin induced a dose-dependent relaxation of phenylephrine-precontracted rat aorta which was abolished by removal of the endothelium. Pretreatment of the endothelium-intact aortic tissues with NG-nitro-L-arginine methylester (L-NAME) or 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one (ODQ) significantly inhibited the vascular relaxation induced by bakuchicin. Incubation with bakuchicin increased the production of cGMP in a concentration-dependent manner, and this effect was blocked by pretreatment with both L-NAME and ODQ. Vascular relaxation induced by bakuchicin was significantly inhibited by pretreatment with verapamil and diltiazem, but not by several other inhibitors including tetraethylammonium (TEA), glibenclamide, indomethacin, atropine or propranolol. These results suggested that bakuchicin-induced vasodilatation is closely associated with the endothelium-dependent nitric oxide (NO)/cGMP signaling pathway, with the possible involvement of L-type Ca(2+) channels.     

Bismuth UPD on the modified Au(1 1 1) electrode

The bismuth UPD was studied on Au(1 1 1) electrodes modified by silver intermediates and adsorbed thymine. Cyclic voltammetry, potential step experiments and X-ray photoelectron spectroscopy were used for investigation. The results were compared to the results of the analogous experiments performed on bare Au(1 1 1) and on bulk silver. In the first part it is shown that the Bi UPD on Ag_ML/Au(1 1 1) differs completely from the UPD on Au(1 1 1) as well as on bulk Ag due to changed electronic properties of the substrate. The 2nd part focuses on the Bi UPD in presence of the nucleobase thymine. Thymine undergoes a reorientation from the chemisorbed state to the physisorbed state on Au(1 1 1) at potentials where the Bi UPD takes place. During the UPD adsorbed thymine is replaced by Bi species on the electrode surface. It does not re-adsorb on top of the deposited Bi layer. An energetic advantage due to re-adsorption on topmost layer as described for the Cu UPD on thymine modified Au(1 1 1) does not occur.     

Electrodeposition and stripping analysis of bismuth selenide thin films using combined electrochemical quartz crystal microgravimetry and stripping voltammetry

Combined stripping voltammetry and electrochemical quartz crystal microgravimetry were employed for the compositional analysis of electrodeposited bismuth selenide (Bi–Se) thin films. Electrodeposited films contain free Bi and free Se in addition to the targeted Bi₂Se₃ compound and the amount of these “impurity” phases depends on the electrodeposition variables. Thus the free Se content was determined using the reduction peak of Se to Se²⁻ obtained during the cathodic scan of films in 0.1 M Na₂SO₄ blank electrolyte. The Se content obtained during the cathodic stripping of Bi₂Se₃ to Bi + Se²⁻ was used for the determination of Bi₂Se₃ content using the assumption of 2:3 compound stoichiometry. Finally, the total Bi content was obtained from the anodic scan and the free Bi content was calculated from the difference between total Bi and the Bi present in Bi₂Se₃. The compositional assays thus obtained from the combined use of stripping voltammetry and EQCM are presented as a function of electrodeposition potential and electrolyte composition. The Bi₂Se₃ content decreased as the deposition potential was decreased (made more negative) and was highest when the electrolyte contained the same molar ratio of Bi³⁺ and Se⁴⁺ species. Unlike the Bi₂Te₃ previously studied by us, electrodeposition of Bi₂Se₃ was not efficient at potentials more negative than −0.5 V because of Se stripping and hydrogen evolution.     

Ghrelin stimulates proliferation of human osteoblastic TE85 cells via NO/cGMP signaling pathway

Ghrelin regulates bone formation and osteoblast proliferation, but the detailed signaling pathway for its action on osteoblasts remains unclear. In human osteoblastic TE85 cells, we observed the effects and intracellular signaling pathway of ghrelin on cell proliferation using BrdU incorporation method. Ghrelin, at 10⁻¹⁰–10⁻⁸ M concentration, significantly increased BrdU incorporation into TE85 cells. The action of ghrelin was inhibited by d-Lys3-GHRP-6, a selective antagonist of GHS-R. Nitric oxide (NO) scavenger hemoglobin and the NO synthase inhibitor NAME eliminated the stimulatory action of ghrelin on proliferation, while NO donor SNAP and NO synthase substrate L-AME stimulated proliferation of osteoblastic TE85 cells. The cGMP analogue, 8-Br-cGMP, stimulated TE85 cell proliferation, and ghrelin did not enhance proliferation in the presence of 8-Br-cGMP. Inhibition of cGMP production by the guanylate cyclase inhibitor prevented ghrelin-induced osteoblastic TE85 cell proliferation. In conclusion, ghrelin stimulates proliferation of human osteoblastic TE85 cells via intracellular NO/cGMP signaling pathway. The authors Deng-Hu Wang and Yun-Sheng Hu contributed equally to this work.     

豚鼠光老化模型的建立和氮氧化物Tempol防护作用的研究

目的 探讨建立豚鼠皮肤的光老化模型及外用氮氧化物Tempol对豚鼠光老化皮肤的保护作用. 方法 以模拟目光光源(SSR)建立豚鼠皮肤的光老化模型,以苏木素一伊红和Weigert染色法及透视电镜观察真皮结构、成纤维细胞和弹力纤维结构的变化.豚鼠在每次照射前外用5mg/ml或0.5 mg/ml的Tempol,探讨Tempol对上述变化的保护作用. 结果 豚鼠以亚红斑量SSR照射17周,光照部位真皮浅层出现了典型的光化性弹力纤维变性损害,成纤维细胞损伤甚至破碎.照射前外用Tempol可以预防上述表现出现,Tempol以5 mg/ml保护作用更强. 结论 利用豚鼠可构建稳定的光老化动物模型,抗氧化剂Tempol对豚鼠皮肤光老化损害有防护作用.     

Alcohol Stimulates Ciliary Motility of Isolated Airway Axonemes Through a Nitric Oxide, Cyclase, and Cyclic Nucleotide-Dependent Kinase Mechanism

Background: Lung mucociliary clearance provides the first line of defense from lung infections and is impaired in individuals who consume heavy amounts of alcohol. Previous studies have demonstrated that this alcohol‐induced ciliary dysfunction occurs through impairment of nitric oxide (NO) and cyclic nucleotide‐dependent kinase‐signaling pathways in lung airway ciliated epithelial cells. Recent studies have established that all key elements of this alcohol‐driven signaling pathway co‐localize to the apical surface of the ciliated cells with the basal bodies. These findings led us to hypothesize that alcohol activates the cilia stimulation pathway at the organelle level. To test this hypothesis we performed experiments exposing isolated demembranated cilia (isolated axonemes) to alcohol and studied the effect of alcohol‐stimulated ciliary motility on the pathways involved with isolated axoneme activation. Methods: Isolated demembranated cilia were prepared from bovine trachea and activated with adenosine triphosphate. Ciliary beat frequency, NO production, adenylyl and guanylyl cyclase activities, cAMP‐ and cGMP‐dependent kinase activities were measured following exposure to biologically relevant concentrations of alcohol. Results: Alcohol rapidly stimulated axoneme beating 40% above baseline at very low concentrations of alcohol (1 to 10 mM). This activation was specific to ethanol, required the synthesis of NO, the activation of soluble adenylyl cyclase (sAC), and the activation of both cAMP‐ and cGMP‐dependent kinases (PKA and PKG), all of which were present in the isolated organelle preparation. Conclusions: Alcohol rapidly and sequentially activates the eNOS→NO→GC→cGMP→PKG and sAC→cAMP→ PKA dual signaling pathways in isolated airway axonemes. These findings indicate a direct effect of alcohol on airway cilia organelle function and fully recapitulate the alcohol‐driven activation of cilia known to exist in vivo and in intact lung ciliated cells in vitro following brief moderate alcohol exposure. Furthermore, these findings indicate that airway cilia are exquisitely sensitive to the effects of alcohol and substantiate a key role for alcohol in the alterations of mucociliary clearance associated with even low levels of alcohol intake. We speculate that this same axoneme‐based alcohol activation pathway is down regulated following long‐term high alcohol exposure and that the isolated axoneme preparation provides an excellent model for studying the mechanism of alcohol‐mediated cilia dysfunction.     

红细胞抗高血压因子和川芎嗪对大鼠血管平滑肌cGMP含量的影响

观察红细胞抗高血压因子（ＡＨＦ）和中药川芎嗪（ＴＭＰ）对血管平滑肌细胞环一磷酸鸟苷（ｃＧＭＰ）产生的影响。方法实验用８～１０周的Ｗｉｓｔａｒ大鼠（ｎ＝６）。分离主动脉（Ａ）及肠系膜动脉（ＭＡ），其中Ａ一半去内皮，另一半保留内皮完整，将肌条分别制备成匀浆，用放射免疫分析法测定ｃＧＭＰ含量。结果ＡＨＦ（１０－５ｇ／ｍｌ）和ＴＭＰ（１０－４ｍｏｌ／Ｌ）对血管平滑肌细胞（ＶＳＭＣ）ｃＧＭＰ生成有显著刺激作用。在ＡＨＦ作用下，Ａ组有、无内皮组和ＭＡ组ｃＧＭＰ含量分别是对照组的１．２５倍，１．２６倍和１．７２倍；在ＴＭＰ作用下的实验组ｃＧＭＰ含量分别为对照组的１．６０倍，１．５０倍和１．５２倍，与对照组比较差异均有显著性（Ｐ＜０．０５或Ｐ＜０．００１）。结论ＡＨＦ和ＴＭＰ均能升高Ａ和ＭＡｃＧＭＰ水平，且ＡＨＦ对阻力血管的影响明显高于容量血管，而ＴＭＰ对两种血管的ｃＧＭＰ水平影响无明显差异，ＡＨＦ与ＴＭＰ对血管ｃＧＭＰ的增高作用似乎与内皮无关。