MicroRNA-10b Promotes Nucleus Pulposus Cell Proliferation through RhoC-Akt Pathway by Targeting HOXD10 in Intervetebral Disc Degeneration

Aberrant proliferation of nucleus pulposus cell is implicated in the pathogenesis of intervertebral disc degeneration. Recent findings revealed that microRNAs, a class of small noncoding RNAs, could regulate cell proliferation in many pathological conditions. Here, we showed that miR-10b was dramatically upregulated in degenerative nucleus pulposus tissues when compared with nucleus pulposus tissues isolated from patients with idiopathic scoliosis. Moreover, miR-10b levels were associated with disc degeneration grade and downregulation of HOXD10. In cultured nucleus pulposus cells, miR-10b overexpression stimulated cell proliferation with concomitant translational inhibition of HOXD10 whereas restored expression of HOXD10 reversed the mitogenic effect of miR-10b. MiR-10b-mediated downregulation of HOXD10 led to increased RhoC expression and Akt phosphorylation. Either knockdown of RhoC or inhibition of Akt abolished the effect of miR-10b on nucleus pulposus cell proliferation. Taken together, aberrant miR-10b upregulation in intervertebral disc degeneration could contribute to abnormal nucleus pulposus cell proliferation through derepressing the RhoC-Akt pathway by targeting HOXD10. Our study also underscores the potential of miR-10b and the RhoC-Akt pathway as novel therapeutic targets in intervertebral disc degeneration.     

hBMP-7基因转染对原代培养兔髓核细胞生物学活性的影响

目的：探讨原代培养的兔髓核细胞转染腺病毒载体介导的人骨形态发生蛋白-7（hBMP-7）基因后对其生物学活性的影响。方法：根据兔髓核细胞转染方式的不同,分为hBMP7组、Lacz组、未转染组三组,hBMP7组采用腺病毒载体介导的hBMP7进行转染,LacZ组转染LacZ基因,未转染组不转染任何基因。比较三组细胞增殖、硫酸糖胺多糖（GAG）产量、Ⅱ型胶原产量有无差异。结果：处理方式和转染后时间对细胞增殖、GAG产量、Ⅱ型胶原产量有交互作用（P〈0．05）,hBMP7组细胞增殖、GAG产量、Ⅱ型胶原产量高于LacZ组、未转染组,差异有统计学意义（P〈0．05）,LacZ组和未转染组细胞增殖、GAG产量、Ⅱ型胶原产量差异无统计学意义（P〉0．05）。结论：hBMP．7基因转染可提高髓核细胞增殖能力,促进其产生细胞外基质。     

扇贝糖胺聚糖对感染HSV-I小鼠免疫功能的影响研究

目的：研究扇贝裙边糖胺聚糖（glycosaminoglycan from Scallop Skirt,SS—GAG）对感染单纯疱疹病毒I型（herpes simplex virustype,HSV-I）小鼠免疫功能的影响。方法：通过在无菌条件下给予小鼠注射扇贝糖胺聚糖SS．GAG,连续11天,并在给药第三天给小鼠腹腔注射HSV—I病毒悬液建立小鼠感染模型,用MTT等方法观察SS—GAG对HSV—I感染小鼠腹腔巨噬细胞吞噬活性的影响、对脾脏指数、胸腺指数的影响以及对脾淋巴细胞转化能力等免疫指标的影响。结果：与病毒对照组相比,扇贝糖胺聚糖SS-GAG低剂量组、中剂量组、高剂量组均能显著增强HSV．I感染小鼠的腹腔巨噬细胞的吞噬活性和HSV—I感染小鼠的脾脏指数和胸腺指数（P〈0．01）,并且能促进其脾淋巴细胞转化增殖能力（P〈0．01）。结论：扇贝糖胺聚糖在体内有一定的抗I型单纯疱疹病毒作用。其抗病毒作用可能与增强机体免疫功能有关。     

The Nucleus of the Intervertebral Disc from Development to Degeneration

The nucleus of the intervertebral disc in humans shows the mostdramatic changes with age of any cartilaginous tissue. It originatesfrom the notochord. In the foetus and infant, the nucleus containsactively dividing and biosynthetically active notochordal cells.The proteoglycans and other matrix components produced havea high osmotic pressure, imbibe water and maintain a hydratedstructure which, though it has little mechanical strength, hasa high swelling pressure which maintains disc turgor. In somespecies, the notochordal cells and the mucoid nucleus pulposuspersist throughout adult life. However by about 4 yr of agein humans, the notochordal cells have disappeared to be replacedby those of chondrocytic appearance but of unknown origin. Thesecells continue to produce proteoglycans but also synthesizesignificant amounts of collagen. The nucleus becomes firmerand less hydrated and loses its transparent appearance. Thecell density of the adult nucleus is very low with cells occupyingless than 0.5% of tissue volume; each cell thus has to turnover and maintain a large domain of extracellular matrix. Thedensity of living cells decreases with age, possibly becauseof problems with nutrient supply to this large avascular tissue.Proteoglycan concentration also falls, and nucleus hydrationdecreases markedly, the disc discolours and in many cases cleftsand fissures form. In most adults, the disc nucleus degenerateseventually to a stage where it can no longer fulfil its mechanicalrole.     

周期性机械应力对髓核细胞增殖和细胞外基质表达的影响

目的：探讨周期性机械应力对髓核细胞增殖和细胞外基质表达的影响。方法：对兔髓核细胞进行体外细胞培养,对细胞施加周期性机械应力（0.25Mpa,0.1Hz）。实验分为2组,不加压组和加压组,不加压组置于单纯旋转式生物反应器内,加压组每天置于周期性机械应力场内2小时。分别于3天,7天检测细胞数目以及聚集蛋白聚糖（aggrecan）和Ⅱ型胶原的基因表达。结果：髓核细胞的增殖和聚集蛋白聚糖、Ⅱ型胶原基因的表达水平与周期性压力密切相关,在周期性机械应力刺激下髓核细胞增殖明显,细胞外基质的分泌增加,组织工程髓核细胞的活性显著提高。结论：周期性机械应力能够显著促进髓核细胞增殖,同时上调聚集蛋白聚糖、Ⅱ型胶原的基因的表达。     

The Effect of a Variable Disc Pad Friction Coefficient for the Mechanical Brake System of a Railway Vehicle

A brake hardware-in-the-loop simulation (HILS) system for a railway vehicle is widely applied to estimate and validate braking performance in research studies and field tests. When we develop a simulation model for a full vehicle system, the characteristics of all components are generally properly simplified based on the understanding of each component’s purpose and interaction with other components. The friction coefficient between the brake disc and the pad used in simulations has been conventionally considered constant, and the effect of a variable friction coefficient is ignored with the assumption that the variability affects the performance of the vehicle braking very little. However, the friction coefficient of a disc pad changes significantly within a range due to environmental conditions, and thus, the friction coefficient can affect the performance of the brakes considerably, especially on the wheel slide. In this paper, we apply a variable friction coefficient and analyzed the effects of the variable friction coefficient on a mechanical brake system of a railway vehicle. We introduce a mathematical formula for the variable friction coefficient in which the variable friction is represented by two variables and five parameters. The proposed formula is applied to real-time simulations using a brake HILS system, and the effectiveness of the formula is verified experimentally by testing the mechanical braking performance of the brake HILS system.     

Assessment of Lumbar Intervertebral Disc Glycosaminoglycan Content by Gadolinium-Enhanced MRI before and after 21-Days of Head-Down-Tilt Bedrest

During spaceflight, it has been shown that intervertebral discs (IVDs) increase in height, causing elongation of the spine up to several centimeters. Astronauts frequently report dull lower back pain that is most likely of discogenic origin and may result from IVD expansion. It is unknown whether disc volume solely increases by water influx, or if the content of glycosaminoglycans also changes in microgravity. Aim of this pilot study was to investigate effects of the spaceflight analog of bedrest on the glycosaminoglycan content of human lumbar IVDs. Five healthy, non-smoking, male human subjects of European descent were immobilized in 6° head-down-tilt bedrest for 21 days. Subjects remained in bed 24 h a day with at least one shoulder on the mattress. Magnetic Resonance Imaging (MRI) scans were taken according to the delayed gadolinium-enhanced magnetic resonance imaging (dGEMRIC) protocol before and after bedrest. The outcome measures were T₁ and ΔT₁. Scans were performed before and after administration of the contrast agent Gd-DOTA, and differences between T₁-values of both scans (ΔT₁) were computed. ΔT₁ is the longitudinal relaxation time in the tissue and inversely related to the glycosaminoglycan-content. For data analysis, IVDs L1/2 to L4/5 were semi-automatically segmented. Zones were defined and analyzed separately. Results show a highly significant decrease in ΔT₁ (p<0.001) after bedrest in all IVDs, and in all areas of the IVDs. The ΔT₁-decrease was most prominent in the nucleus pulposus and in L4/5, and was expressed slightly more in the posterior than anterior IVD. Unexpected negative ΔT₁-values were found in Pfirrmann-grade 2-discs after bedrest. Significantly lower T₁ before contrast agent application was found after bedrest compared to before bedrest. According to the dGEMRIC-literature, the decrease in ΔT₁ may be interpreted as an increase in glycosaminoglycans in healthy IVDs during bedrest. This interpretation seems contradictory to previous findings in IVD unloading.     

The Effect of Cotinine on Nicotine- and Cocaine-InducedDopamine Release in the Nucleus Accumbens

Cotinine is the major metabolite of nicotine. Nicotine is rapidly metabolized and has a short half-life, but cotinine is metabolized and eliminated at a much lower rate. Because of the resulting increase with time in the cotinine to nicotine ratio in the body, including in the brain, it is of interest to examine the effect of cotinine on nicotine-induced changes. In studies on conscious, freely-moving rats, intravenous administration of either nicotine or cocaine induced the release of dopamine in the nucleus accumbens, as assayed by microdialysis. Prior intravenous administration of a high dose of cotinine (500 microg/kg) inhibited this nicotine- or cocaine-induced dopamine release. The action of cotinine does not seem to occur through its effect on the metabolism of nicotine or on its binding at the receptor site, because cotinine, unlike nicotine, does not affect the binding of the nicotinic ligand cytisine. The findings suggest that cotinine affects a putative component of the reward mechanism, and as such could have therapeutic value.     

The Vertebrate Body Axis: Evolution and Mechanical Function

The body axis of vertebrates is an integrated cylinder of bones,connective tissue, and muscle. These structures vary among livingand extinct vertebrates in their orientation, composition, andfunction in ways that render useless simplistic models of theselective pressures that may have driven the evolution of theaxis. Instead, recent experimental work indicates that the vertebrateaxis serves multiple mechanical functions simultaneously: bendingthe body, storing elastic energy, transmitting forces from limbs,and ventilating the lungs. On the biochemical level, researchon human intervertebral discs has shown that collagens resisttension and torsion while proteoglycans bind water to resistcompression. This molecular behavior predicts mechanical behaviorof the entire joint, which, in turn helps determine the mechanicalbehavior of the vertebral column. The axial skeleton, in turn,is reconfigured by axial muscles that work by way of three-dimensionalconnective tissues that derive mechanical advantage for themuscle force by using the skin to increase leverage. Modelsmay eventually help determine which evolutionary changes inthe vertebrate body axis have had important functional and possiblyadaptational consequences. Current reconstruction of the hypotheticalstem lineage of early chordates and vertebrates suggests thatthe gradual mineralization of the vertebral elements, appearanceof fin rays and new median fins, and transverse and then horizontalsegmentation of the axial musculature are all features correlatedwith increases in swimming speed, maneuverability, and bodysize.     

Anaerobic Degradation of the Benzene Nucleus by a Facultatively Anaerobic Microorganism

A bacterium was isolated by elective culture with p-hydroxybenzoate as substrate and nitrate as electron acceptor. It grew either aerobically or anaerobically, by nitrate respiration, on a range of aromatic compounds. The organism was identified as a pseudomonad and was given the trivial name Pseudomonas PN-1. Benzoate and p-hydroxybenzoate were metabolized aerobically via protocatechuate, followed by meta cleavage catalyzed by protocatechuic acid-4,5-oxygenase, to yield alpha-hydroxy-gamma-carboxymuconic semialdehyde. Pseudomonas PN-1 grew rapidly on p-hydroxybenzoate under strictly anaerobic conditions, provided nitrate was present, even though protocatechuic acid-4,5-oxygenase was repressed. Suspensions of cells grown anaerobically on p-hydroxybenzoate oxidized benzoate with nitrate and produced 4 to 5 mumoles of CO(2) per mumole of benzoate added; these cells did not oxidize benzoate aerobically. The patterns of the oxidation of aromatic substrates with oxygen or nitrate by cells grown aerobically or anaerobically on different aromatic compounds indicated that benzoate rather than protocatechuate was a key intermediate in the early stages of anaerobic metabolism. It was concluded that the pathway for the anaerobic breakdown of the aromatic ring is different and quite distinct from the aerobic pathway. Mechanisms for the anaerobic degradation of the benzene nucleus by Pseudomonas PN-1 are discussed.