Wound healing activity of Delonix elata stem bark extract and its isolated constituent quercetin-3-rhamnopyranosyl-(1-6) glucopyranoside in rats

Delonix elata L.is a Ceasalpinaceae species and is traditionally used in India for treatment of skin diseases,liver diseases and rheumatic problems.However,systematic evaluation of its wound healing activity is lacking.Thus,in the present study,we aimed to assess the wound healing activity of D.elata stem bark extract(DSE) and its isolated constituent quercetin-3-rhamnopyranosyl-(1-6) glucopyranoside(QRPG) in rats.The formulations effects on wound healing were assessed by the wound contraction rate,epithelialization period,tensile strength,content of the hydroxyproline,hexosamine and uronic acid in granulation tissue,histopathological studies and Col 1 α(I) expression level in wound tissue by reverse transcription polymerase chain reaction(RT-PCR) study.The topical application of DSE ointment caused faster epithelialization,significant wound contraction(100%),and better tensile strength(710.5 ± 10.5 g/cm^2),while QRPG showed wound epithelialization with 98.2%contraction,better than that of the control group(78.18%).The biochemical analysis of granulation tissue revealed that DSE and QRPG significantly increased hydroxyproline,hexosamine and uronic acid content.A significant increase in the expression of Col 1 α(I) was observed in the wound tissue of DSE and QRPG treated rats.DSE and QRPG were shown to enhance wound healing by increasing collagen synthesis through upregulation of Col 1 α(I),thus validating ethnomedicinal uses.

Process for improving the ladle free- opening rate for high aluminum steel in continuous casting

Steel 20Mn23AlV is a type of high aluminum steel with a very low ladle free-opening rate. The aluminum composition of 20Mn23AlV ranges from 1.6% to 2.45% ,which is significantly higher than other types of steel. According to the real condition of 40 t ladle in steel-making plant of Baosteel Special Steel Company, previous works show that the key factors affecting the ladle free-opening rate of high aluminum steel in continuous casting are：sand material, accessories baking, ladle nozzle cleaning, the process and amount of adding sand, and the rate of argon stirring during refining. Therefore, improving the ladle filler sand quality, baking all of the raw materials, controlling the addition of ladle filler sand, cleaning the ladle nozzle, and optimizing argon stirring during the refining process can resolve the problem of a low ladle free-opening rate of high aluminum steel caused by the long ladle time of liquid steel.

Effect of varying normal stress on stability and dynamic motion of a spring-slider system with rate- and state-dependent friction

Incorporating rate and state friction laws, stability of linearly stable （i.e., with stiffness greater than the critical value） spring-slider systems subjected to triggering perturbations was analyzed under variable normal stress condition, and comparison was made between our results and that of fixed normal stress cases revealed in previous studies. For systems associated with the slip law, the critical mag- nitude of rate steps for triggering unstable slips are found to have a similar pattern to the fixed normal stress case, and the critical velocity steps scale with a/（b - a） when k = kcr for both cases. The rate-step boundaries for the variable normal stress cases are revealed to be lower than the fixed normal stress case by 7 %-16 % for a relatively large ct = 0.56 with （b - a）/a ranging from 0.25 to 1, indicating easier triggering under the variable normal stress condition with rate steps. The difference between fixed and variable normal stress cases decreases when the α value is smaller. In the same slip- law-type systems, critical displacements to trigger instability are revealed to be little affected by the variable normal stress condition. When k 〉 kcr（V,）, a spring-slider system with the slowness law is much more stable than with the slip law,suggesting that the slowness law fits experimental data better when a single state variable is adopted. In stick-slip motions, the variable normal stress case has larger stress drops than the constant normal stress case. The variable normal stress has little effect on the range of slip velocity in systems associated with the slowness law, whereas systems associated with the slip law have a slowest slip velocity immensely smaller than the fixed normal stress case, by ~ 10 orders of magnitude.

Effect of cooling rate on evolution of superconducting phases during decomposition and recrystallization of (Bi,Pb)-2223 core in Ag-sheathed tape

The reformation of (Bi,Pb)-2223 from the liquid or melt is very important for a melting process of (Bi,Pb)-2223 tape. By combination of quenching experiment with X-ray diffraction (XRD) analysis, the effect of cooling rate on the evolution of three superconducting phases in the (Bi,Pb)-2223 core of Ag-sheathed tape was investigated. The results show that (Bi,Pb)-2223 reformation from the melt seems to experience different routes during slowly cooling at different rates. One is that (Bi,Pb)-2223 phase reformed directly from the melt, and no Bi-2212 participate in this process. The other is that (Bi,Pb)-2223 is converted from the intermediate product, Bi-2212, which formed from the melt during the first cooling stage. Due to the inherent sluggish formation kinetics of (Bi,Pb)-2223 from Bi-2212, only partial (Bi,Pb)-2223 can finally be reformed with the second route.

Plastic Flow Modeling of Ti-5 Al-2 Sn-2 Zr-4 Mo-4 Cr Alloy at Elevated Temperatures and High Strain Rates

The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.

Performance Analysis of Outage Probability and Error Rate of Square M-QAM in Mobile Wireless Communication Systems over Generalized α-μ Fading Channels with Non-Gaussian Noise

This paper derives new and exact closed-form expressions for the average symbol error rate(SER) of square M-ary quadrature amplitude modulation(M-QAM) in wireless communication systems over theα-μfading channels subject to an additive non-Gaussian noise. The obtained expressions take into account static and mobile wireless receivers. In addition, a closed-form expression for the outage probability in mobile networks is obtained. Please note that all derived expressions in this paper a valid for integer and non-integer values of the fading parameters. Analytical results are presented to study the impact of noise shaping parameter, severity of fading, and mobility on the average SER. Monte-Carlo simulations results are also provided to validate the accuracy of the analytical results.

聚脲甲醛-生物油微胶囊的研制及性能探究

为研究微胶囊对沥青路面微裂纹的愈合效果,首先利用聚脲甲醛(作为微胶囊壁)和生物油(作为微胶囊心)采用原位聚合法制备微胶囊,采用扫描/透射电子显微镜和热重分析探究微胶囊的外观形貌和热稳定性;然后将微胶囊用于制备微胶囊/苯乙烯-丁二烯-苯乙烯(styrene-butadiene-styrene, SBS)复合改性沥青,通过动态剪切流变仪和离析试验探究微胶囊的掺加对复合改性沥青路面性能的影响;最后通过延度愈合率试验验证微胶囊的愈合效果,并结合宏微观试验分析其愈合机理。结果表明:微胶囊呈现类球状,且表面较为粗糙,增大了与沥青的接触面积。微胶囊的热稳定性较好,其囊壁可承受沥青混合料生产过程中的高温环境。随着微胶囊的添加,复合改性沥青的低温塑性和耐热性均有所改善。此外,复合改性沥青的储能模量和损失模量也有所提升,即微胶囊的添加提升了SBS改性沥青的黏弹性能,这可能是由于添加的微胶囊与SBS和基质沥青具有很好的相容性,且微胶囊均匀分散在沥青内部并嵌入SBS呈现的网状结构中,这也在离析试验和荧光显微试验中得以证实。当微胶囊的掺量为0.4%时,复合改性沥青的愈合率达到最高。

NO_3^-/NH_4^+ ratios affect plant growth, chlorophyll content,respiration rate, and morphological structure in Malus hupehensis seedlings

Malus hupehensis （Pamp.） Rehd. is a widely cultivated rootstock in China. We studied the effect of three NO3-/NH4＋ ratios （100/0, 50/50, and 0/100, molar basis） at total nitrogen （N） concentration of 8 mmoL L-1 in a nutrient solution on M. hupehensis seedlings. Plant biomass, NO3- and NH4＋concentrafion, chlorophyll con- tent, respiratory rate, and cellular structure were investi- gated. M. hupehensis seedlings at the NO3-/NH4＋ ratio of 50/50 had the highest level of fresh weight, dry weight, shoot length, and chlorophyll （a, b, and a ＋ b） content, but the lowest respiration rate in the leavesand roots. In addition, thickness and numbers of palisade and spongy tissue cells of the leaves were greater with this treatment than with other treatments. At the NO3-/NH4＋ ratio of 100/0, the leaves and roots had higher NO3- concentration and lower NH4＋ concentration. However, the opposite trend occurred at the NO3-/NH4＋ ratio of 0/100. Chloro- phyll （a, b, and a ＋ b） content was lowest at the NO3-/NH4＋ ratio of 100/0 than at the other ratios. At the NO3-/ NH4＋ ratio of 0/100, oxygen （02） consumption increased in the leaves and roots, and irregular epidermis and cortex cells were observed in the root apical meristematic and mature region. Our results indicated that the NO3-INH4＋ ratio at 50/50 was suitable for growth of M. hupehensis seedling to achieve the highest biomass production and efficiency.

THE BROAD-BAND CCD PHOTOMETRY AND DUST PRODUCTION RATES OF COMET HALE-BOPP

Based upon broad-band CCD observation data of comet Hale-Bopp obtained by a 60cm telescope at Xinglong Station of Beijing Astronomical Observatory during March-August, 1996, the photometric results of comet Hale-Bopp are reported. Using the photometric results, the dust production rate, radius and mass of nucleus of comet Hale-Bopp are estimated as follows: dM/dt～1.5×10 5 kgs -1, R n～35.5km, and M n～5.65×10 16kg.

Diagnostic performance of dynamic contrast-enhanced magnetic resonance imaging parameters and serum tumor markers in rectal carcinoma prognosis

BACKGROUND Rectal carcinoma(RC),one of the most common malignancies globally,presents an increasing incidence and mortality year by year,especially among young people,which seriously affects the prognosis and quality of life of patients.At present,dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)parameters and serum carbohydrate antigen 19-9(CA19-9)and CA125 Levels have been used in clinical practice to evaluate the T stage and differentiation of RC.However,the accuracy of these evaluation modalities still needs further research.This study explores the application and value of these methods in evaluating the T stage and differentiation degree of RC.AIM To analyze the diagnostic performance of DCE-MRI parameters combined with serum tumor markers(TMs)in assessing pathological processes and prognosis of RC patients.METHODS A retrospective analysis was performed on 104 RC patients treated at Yantai Yuhuangding Hospital from May 2018 to January 2022.Patients were categorized into stages T1,T2,T3,and T4,depending on their T stage and differentiation degree.In addition,they were assigned to low(L group)and moderate-high differentiation(M+H group)groups based on their differentiation degree.The levels of DCE-MRI parameters and serum CA19-9 and CA125 in different groups of patients were compared.In addition,the value of DCE-MRI parameters[volume transfer constant(Ktrans),rate constant(Kep),and extravascular extracellular volume fraction(Ve)in assessing the differentiation and T staging of RC patients was discussed.Furthermore,the usefulness of DCE-MRI parameters combined with serum CA19-9 and CA125 Levels in the evaluation of RC differentiation and T staging was analyzed.RESULTS Ktrans,Ve,CA19-9 and CA125 were higher in the high-stage group and L group than in the low-stage group and M+H Group,respectively(P<0.05).The areas under the curve(AUCs)of the Ktran and Ve parameters were 0.638 and 0.694 in the diagnosis of high and low stages,respectively,and 0.672 and 0.725 in diagnosing moderate-high and low differentiation,respectively.The AUC of DCE-MRI parameters(Ktrans+Ve)in the diagnosis of high and low stages was 0.742,and the AUC in diagnosing moderate-high and low differentiation was 0.769.The AUCs of CA19-9 and CA-125 were 0.773 and 0.802 in the diagnosis of high and low stages,respectively,and 0.834 and 0.796 in diagnosing moderate-high and low differentiation,respectively.Then,we combined DCE-MRI(Ktrans+Ve)parameters with CA19-9 and CA-125 and found that the AUC of DCE-MRI parameters plus serum TMs was 0.836 in the diagnosis of high and low stages and 0.946 in the diagnosis of moderate-high and low differentiation.According to the Delong test,the AUC of DCE-MRI parameters plus serum TMs increased significantly compared with serum TMs alone in the diagnosis of T stage and differentiation degree(P<0.001).CONCLUSION The levels of the DCE-MRI parameters Ktrans and Ve and the serum TMs CA19-9 and CA125 all increase with increasing T stage and decreasing differentiation degree of RC and can be used as indices to evaluate the differentiation degree of RC in clinical practice.Moreover,the combined evaluation of the above indices has a better effect and more obvious clinical value,providing important guiding importance for clinical condition judgment and treatment selection.

High Strain Rate Induced Plasticity-increasing of Metallic Materials under Tension

The effect of strain rate on plasticity has been Investigat-ed for three metallic materials with dynamic tension tech-nique. A phenomenon of high strain induced plasticity -increasing was found for tested materials. The elongation of quenched 30CrMnSiNi2A is 14. 5% under 40 m/s loading rate which is more than two times of the 7 % un-der 0. 5 mm/min. This typic high strain rate induced plasticity - Increasing phenomenon is associated with adiabatic heating, strain twinning and suppression of strain - induced - phase transformation.

Rh-bFGF在创伤性鼓膜穿孔中的临床应用

目的分析重组人碱性成纤维细胞生长因子在创伤性鼓膜穿孔中的临床疗效。方法搜集2014年3月~2017年10月就诊于我科门诊的外伤性鼓膜穿孔患者155例(161耳)。随机分为三组:A组(51耳)、B组(52耳)、C组(58耳),分析、比较各组在2、4周时的鼓膜愈合率、平均愈合时间、平均纯音听阈(PTA)。结果各组在2、4周时的鼓膜愈合率、平均愈合时间、PTA比较差异均有统计学意义(P<0.05)。结论创伤性鼓膜穿孔中,Rh-bFGF可显著提高穿孔愈合率,缩短愈合时间,更好的提高听力恢复,值得推广应用。

重组人粒细胞-巨噬细胞集落刺激因子凝胶对大鼠深Ⅱ度烫伤创面愈合的实验研究

目的探讨重组人粒细胞-巨噬细胞集落刺激因子凝胶对深Ⅱ度烫伤创面的影响及促进创面愈合的作用机制。方法 40只大鼠采用相同的方法在背部制成深Ⅱ度烫伤,随机分成实验组和对照组,实验组为rhGM-CSF凝胶治疗组,对照组为0.5‰碘溶液治疗组,各组每天给药1次,连用13天。伤后4、7、10、13天各组随机选取5只大鼠处死,计算创面愈合率、成纤维细胞含量、胶原含量和微血管密度计数。结果伤后4天,实验组与对照组创面愈合率比较无明显差异(P>0.05);伤后7、10、13天,实验组均优于对照组(P<0.05)。伤后4、7、10天,实验组成纤维细胞含量均高于对照组(P<0.05),但伤后13天,实验组低于对照组(P<0.05)。伤后4、7、10、13天,实验组胶原含量均高于对照组(P<0.05)。伤后4、7、10、13天,实验组微血管密度计数均高于对照组(P<0.05)。结论外用重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)通过促进微血管生长、促进成纤维细胞的形成及创面胶原的形成来增加创面愈合速度及改善修复质量,与传统的外用碘伏纱布包扎换药治疗相比能明显缩短治疗过程。

上调miR-210对糖尿病足模型大鼠的干预效果及作用机制研究

目的上调微小RNA-210(miR-210)对糖尿病足模型大鼠的干预效果及相关作用机制。方法选取健康、清洁级SD雄性大鼠40只,随机选取10只为空白组,剩余30只建立糖尿病足模型,成功27只随机分为模型组、阴性对照组、miR-210上调组,各9只。采用实时荧光定量PCR检测miR-210表达,统计创面愈合率,观察病理组织,酶联免疫吸附法(ELISA)检测炎性因子、血管内皮活性相关因子水平,采用免疫印迹(Western blot)检测VEGF-PI3K/AKT-eNOS信号通路相关蛋白表达。结果模型组、阴性对照组、miR-210上调组miR-210表达均低于空白组;且miR-210上调组miR-210表达最高(P<0.05)。模型组、阴性对照组、miR-210上调组干预后3 d、干预后5 d创面愈合率均低于空白组,且miR-210上调组干预后3 d、干预后5 d创面愈合率最高(P<0.05)。4组干预后5 d创面愈合率均高于干预后3 d(P<0.05)。干预后5 d,模型组、阴性对照组、miR-210上调组IL-18、TNF-α、VCAM-1、ET水平均高于空白组,NO、NOS水平低于空白组,且miR-210上调组差异最明显(P<0.05)。干预后5 d,模型组、阴性对照组、miR-210上调组VEGF、SDF1α、AKT、eNOS表达均高于空白组,且miR-210上调组VEGF、SDF1α、AKT、eNOS表达最低(P<0.05)。结论上调miR-210能提高糖尿病足模型大鼠创面愈合率,抑制炎性反应,改善血管内皮活性,其作用机制可能与VEGF-PI3K/AKT-eNOS信号通路有关。

rh-aFGF卡波姆940凝胶对1型糖尿病大鼠皮肤创伤的修复作用

目的研究重组人酸性成纤维细胞生长因子(recombinant human acidic fibroblast growth factor,rh-aFGF)卡波姆940凝胶对糖尿病大鼠皮肤创伤修复作用。方法使用STZ诱导产生SD大鼠糖尿病模型,建立全层皮肤切除和烫伤两种皮肤创伤模型,设置对照组、赋形剂组、90 AU rh-aFGF凝胶组和270 AU rh-aFGF凝胶组4个实验组。用创伤面积和愈合速率评价各组疗效;HE染色观察创面中成纤维细胞、肌成纤维细胞、胶原纤维和毛细血管生长情况;半定量评分评价rh-aFGF诱导的上述指标生长情况。结果 rh-aFGF卡波姆940凝胶明显减少糖尿病SD大鼠全层皮肤切除和烫伤模型的皮肤损伤面积(P<0.05),促进其创伤愈合速率(P<0.05)。HE染色结果表明,rh-aFGF卡波姆凝胶明显促进成纤维细胞和胶原纤维增殖评分(P<0.05)。结论 rh-aFGF卡波姆凝胶可能在一定程度上保护创面微环境和保护rhaFGF发挥生物学活性,促进成纤维细胞增殖和胶原纤维沉积,从而促进糖尿病SD大鼠皮肤创伤愈合过程,有望成为一种治疗糖尿病溃疡的新制剂。

白竭散对肛瘘术后急性感染性创面模型大鼠ICAM-1、TNF-α表达水平的影响

目的 造肛瘘术后急性感染创面模型大鼠,并观察白竭散对其创面愈合的影响。方法 将64只清洁SD大鼠随机分为空白组、模型组、白竭散组、贝复济组。除空白组外,其余各组在大鼠肛门处制作急性感染性创面模型。白竭散组与贝复济组以对应药物每日进行治疗。空白组和模型组则以生理盐水棉球清创治疗。观察大鼠的基本状况、计算不同时间创面愈合率、采用激光多普勒血流计记录不同时间点创面的动态血流情况、酶联免疫法(ELISA)检测创面组织中细胞间黏附分子-1(ICAM-1)、肿瘤坏死因子-α(TNF-α)蛋白表达。结果 第7、10、14天,与模型组相比,白竭散组与贝复济组大鼠创面愈合率明显更高(P <0.05),且白竭散组创面愈合率明显高于贝复济组(P <0.05);各时间点白竭散组与贝复济组大鼠创面血流运行状态均明显优于模型组(P <0.05),且模型组低于空白组(P <0.05);与模型组比较,治疗结束后白竭散组大鼠创面组织中ICAM-1、TNF-α的表达量降低尤为明显(P <0.05)。结论 白竭散可显著提高创面愈合率,改善局部血流供应,减轻创面的炎症反应。

A two-parameter model to predict fatigue life of high-strength steels in a very high cycle fatigue regime

In this paper, ultrasonic （20 kHz） fatigue tests were performed on specimens of a high-strength steel in very high cycle fatigue （VHCF） regime. Experimental results showed that for most tested specimens failed in a VHCF regime, a fatigue crack originated from the interior of specimen with a fish-eye pattern, which contained a fine granular area （FGA） centered by an inclusion as the crack origin. Then, a two-parameter model is proposed to predict the fatigue life of high-strength steels with fish-eye mode failure in a VHCF regime, which takes into account the inclusion size and the FGA size. The model was verified by the data of present experiments and those in the literature. Furthermore, an analytic formula was obtained for estimating the equivalent crack growth rate within the FGA. The results also indicated that the stress intensity factor range at the front of the FGA varies within a small range, which is irrespective of stress amplitude and fatigue life.

Rates of bacterial sulfate reduction and their response to experimental temperature changes in coastal sediments of Qi'ao Island, Zhujiang River Estuary in China

Subtropical sediment cores （QA09-1 and QA12-9） from the coastal zone of Qi’ao Island in the Zhujiang River Estuary were used to determine the rates of sulfate reduction and their response to experimental tempera-ture changes. The depth distribution of the sulfate reduction rates was measured from whole-core incu-bations with radioactive tracer35SO42-, and peaks of 181.19 nmol/（cm3·d） and 107.49 nmol/（cm3·d） were exhibited at stations QA09-1 and QA12-9, respectively. The profiles of the pore water methane and sulfate concentrations demonstrated that anaerobic oxidation of methane occurred in the study area, which result-ed in an increase in the sulfate reduction rate at the base of the sulfate-reducing zone. Meanwhile, the sulfate concentration was not a major limiting factor for controlling the rates of sulfate reduction. In addition, the incubation of the sediment slurries in a block with a temperature gradient showed that the optimum tem-perature for the sulfate reduction reaction was 36°C. The Arrhenius plot was linear from the lowest tempera-ture to the optimum temperature, and the activation energy was at the lower end of the range of previously reported values. The results suggested that the ambient temperature regime of marine environments prob-ably selected for the microbial population with the best-suited physiology for the respective environment.

A comparative study on crash-influencing factors by facility types on urban expressway

This study aims at identifying crash-influencing factors by facility type of Nagoya Urban Expressway, considering the interaction of geometry, traffic flow, and ambient conditions. Crash rate （CR） model is firstly developed separately at four facility types： basic, merge, and diverge segments and sharp curve. Traffic flows are thereby categorized, and based on the traffic categories, the significances of factors affecting crashes are analyzed by principal component analysis. The results reveal that, the CR at merge segment is significantly higher than those at basic and diverge segments in uncongested flow, while the value is not significantly different at the three facility types in congested flow. In both un- and congested flows, sharp curve has the worst safety performance in view of its highest CR. Regarding influencing factors, geometric design and traffic flow are most significant in un- and congested flows, respectively. As mainline flow increases, the effect of merging ratio affecting crash is on the rise at basic and merge segments as opposed to the decreasing significance of diverging ratio at diverge segment. Mean- while, longer acceleration and deceleration lanes are adverse to safety in uncongested flow, while shorter acceleration and deceleration lanes are adverse in congested flow. Due to its special geometric design, crashes at sharp curve are highly associated with the large centrifugal force and heavy restricted visibility.

THE CENTRAL DISTRIBUTION OF ADRENOMEDULLIN AND ITS EFFECTS ON BLOOD PRESSURE AND HEART RATE IN RATS

The present study was designed to make certain whether there exists adrenomedullin (ADM) in the rat central nervous system and evaluated the hemodynamic actions of intracerebroventricular administration (ICVA) of human ADM[13-52]. By immunohistochemistry (ABC method),We found that there was a discrete localization of ADM-positive immunoreactivity in the rat central system including cerebral cortex,paraventricular tissues, hypothalamus, cerebella cortex, mesencephalon and medulla oblongata. By reverse transcription-polymerase chain reaction(RT-PCR) analysis, rat ADM mRNA was found to be expressed in rat brain. These above results of immunohistochemistry and RT-PCR suggest that ADM exists in the rat brain. We also found that centrally administered ADM[13-52]in a dose of 0.4 to 3. 2 nmol/kg provoked marked, prolonged and dosedependent increases in mean arterial blood pressure (MABP) and heart rate (HR). To clarify the mechanisms of the hemodynamic changes induced by centrally administered ADM [13-52]. the effect of centrally administered ADM [13-52] on renal sympathetic nerve activity (RSNA) was studied. The result showed that centrally administered ADM [13-52] ( 1. 6 nmol/kg) provoked a marked increase in RSNA .therefore .the increases in MABP and HR induced by centrally administered ADM [13-52]might be due to the stimulation of central sympathetic mechanism. In addtion,we also compared the relationship of activity and structure among the different fragments of ADM. In conclusion, ADMexists in the rat brain, and it may play an important role in the central control of cardiovascular system.