Fetal umbilical vein transplantation for the repair of middle cerebral artery injury

It is necessary to investigate the longitudinal tensile mechanical characteristics of the middle cere- bral artery and the fetal umbilical vein prior to applying fetal umbilical vein transplantation for repair of injured middle cerebral artery. Fifteen fresh fetal umbilical vein specimens and 15 normal human fresh cadaver middle cerebral artery specimens were collected for longitudinal tensile testing at the speed of 0.5 mm/min and at normal human temperature. The results showed that under 16.0 kPa physiological stress, the strain value of fetal umbilical vein specimens was larger, while the maximal stress and elastic modulus values were less than those of middle cerebral artery specimens. Our findings indicate that fetal umbilical vein has good elastic properties and the stress-strain curve of the fetal umbilical vein is similar to that of the middle cerebral artery. Fetal umbilical vein transplan- tation can, therefore, potentially repair the injured middle cerebral artery.     

脑动脉粥样硬化模型大鼠大脑中动脉的蠕变

背景：蠕变是生物材料黏弹性固体的表现形式之一,脑动脉硬化和脑出血的防治有必要了解脑动脉硬化大脑中动脉的蠕变力学特性。 目的：比较正常和动脉粥样硬化动物模型大脑中动脉的蠕变力学特性,确定动脉粥样硬化对大脑中动脉蠕变特性的影响。 方法：SD雄性大鼠随机分为两组,模型组肌注维生素D3+尼古丁灌胃+高脂饮食制备动脉粥样硬化模型,对照组正常饮食,4周后处死大鼠取大脑中动脉为标本试件。在日本岛津电子万能试验机上对正常和动脉粥样硬化动脉标本试样进行蠕变实验。蠕变实验的应力增加速度为0.01 MPa/s。设定实验时间为7 200 s,采集100个数,以一元线性回归分析的方法处理实验数据,记录蠕变曲线和数据,以及应变与时间的变化规律。 结果与结论：正常和动脉粥样硬化大鼠大脑中动脉蠕变最初600 s变化较快,之后应变缓慢下降,正常动脉标本7 200 s蠕变量高于动脉粥样硬化动脉标本(50.38%,48.26%,P < 0.05)。说明正常和动脉粥样硬化大鼠大脑中动脉具有不同的蠕变力学特性,提示蠕变曲线是以指数关系变化的,动脉粥样硬化对大脑中动脉蠕变特性具有一定影响。     

Viscoelasticity of repaired sciatic nerve by poly（lactic-co-glycolic acid） tubes

Medical-grade synthetic poly（lactic-co-glycolic acid） polymer can be used as a biomaterial for nerve repair because of its good biocompatibility, biodegradability and adjustable degradation rate. The stress relaxation and creep properties of peripheral nerve can be greatly improved by repair with poly（lactic-co-glycolic acid） tubes. ＂Fen sciatic nerve specimens were harvested from fresh corpses within 24 hours of death, and were prepared into sciatic nerve injury models by creating a 10 mm defect in each specimen. Defects were repaired by anastomosis with nerve autografts and poly（lactic-co-glycolic acid） tubes. Stress relaxation and creep testing showed that at 7 200 seconds the sciatic nerve anastomosed by poly（lactic-co-glycolic acid） tubes exhibited a greater decrease in stress and increase in strain than those anastomosed by nerve autografts. These findings suggest that poly（lactic-co-glycolic acid） exhibits good viscoelasticity to meet the biomechanical require- ments for a biomaterial used to repair sciatic nerve injury.     

多层螺旋CT血管成像评价肝移植受者移植前后血管结构

背景：多层螺旋CT具有先进的扫描技术和强大的图像后处理功能,其亚秒级的扫描速度及各向同性的成像功能,在血管成像上有很多优势。 目的：探讨多层螺旋CT血管成像技术对肝移植受者移植前后血管结构评价的应用价值。 设计、时间及地点：回顾性分析,以肝移植受者肝脏血管为观察对象,自身对照观察,于2003-10/2006-12在中山大学附属第五医院放射科完成。 对象：选择拟行原位肝移植患者27例,年龄31~67岁,男17例,女10例。 方法：轴位螺旋扫描范围为膈顶上方2 cm至双肾下极以下。电压120 kV,动脉期准直0.75 mm,平扫、门脉期、肝静脉期准直1.5 cm;使用非离子型对比剂优维显,注射速度为3 mL/s,三期增强扫描延迟时间分别为20~25 s,50~55 s,75~80 s。重建增强的薄层图像序列,动脉期层厚1 mm,间隔0.7 mm;门脉期、肝静脉期层厚2 mm,间隔1 mm。将图像序列传入后处理工作站,以MIP、VR等方式显示腹腔干系、门脉系、肝静脉及下腔静脉血管的三维结构。 主要观察指标：肝移植前后患者血管三维结构。 结果：移植前所有患者腹腔干系均得到良好显示,21例肝动脉走形正常,6例患者肝动脉变异,其中门静脉海绵样变2例,门脉多发血栓1例,因不适宜手术此3例未进行肝移植。24例患者第二肝门及下腔静脉肝内段血管结构显示清楚,肝右静脉单独汇入下腔静脉、肝左静脉和肝中静脉先汇合后再注入下腔静脉18例,肝右静脉、肝中静脉及肝左静脉分别单独汇入下腔静脉6例,下腔静脉肝后段狭窄2例。17例肝移植后CT血管成像发现肝动脉吻合口部狭窄2例,门脉高压侧支迂曲缓解10例,另7例患者因检查费用问题选择B超检查。 结论：多层螺旋CT血管成像能够清晰显示肝移植患者移植前后血管结构,对适宜手术的病例筛选、指导手术方案及移植后血管结构的评价具有重要意义。     

Intracranial vessels with color Doppler echoencephalography in infants

A technique for imaging of the intracranial vessels in infants was described, which used high resolution, commercially available, color Doppler ultrasonography (real-time two-dimensional Doppler). On 12 normal infants, serial scans were obtained in sagittal, coronal, and axial plains. A large number of intracranial arteries and veins could be clearly demonstrated in real-time, including anterior cerebral artery, pericallosal artery, middle cerebral artery, posterior cerebral artery, basilar artery, communicating artery, internal cerebral vein, inferior and superior sagittal sinuses, great cerebral vein, straight sinus, occipital sinus and transverse sinus. In conclusion, color Doppler examination is useful in the detection of vessels in infants and in the measurement of intracranial blood flow velocity.     

Developmental and radiological anatomy of the superficial cerebral convexity vessels in the human fetus

The superficial cerebral vessels on the convex side of the cerebral hemisphere were investigated using 40 brains of aborted human fetuses (ranging from 2 to 7 months of gestational age), injected with radiopaque material either through the arterial or venous system. These brains, particularly their vessels, were studied in detail through stepwise roentgenography in stereo-pairs, photography and careful dissections. Morphological changes of the superficial vessels of the cerebral convexity reflect the developmental alterations of the cerebral structures, particularly those of the opercula and cerebral sulci. Between the gestational ages of 3 and 4 months, the middle cerebral artery and its tributaries run radially on the sylvian fossa and over the convexity. Anastomoses among the peripheral branches of the anterior, middle and posterior cerebral arteries take place on the convex side of the hemisphere. At the ages of 3 and 4 months, the middle cerebral vein and its tributaries are well developed compared with the superior and inferior cerebral (or ascending and descending cortical) veins. The middle cerebral vein and its tributaries rapidly regress from the 5th to 7th month. The superior and inferior cerebral veins, on the other hand, develop rapidly during this period. Owing to the development of the opercula and resultant depression of the insula, after seven months of gestation the middle cerebral artery and its branches, begin to differentiate into the vallecular (related to the sylvian vallecula or fronto-temporal notch), insular (related to the insular cortex), opercular (related to the frontal, parietal and temporal opercula) and convexity segments (related to the convex side of the hemisphere). The anastomotic veins of Trolard and Labbé are also recognizable at this stage. The superficial sylvian vein in the process of formation may also be detected. The configuration of the cerebral vessels on the convex side of the hemisphere is also affected greatly by the development of the cerebral sulci. These cerebral vessels may run along, or dip into the sulci. Since the development of the superficial cerebral vessels is closely related to that of the cerebral mantle, these studies should be correlated to detail with those of developmental alterations of the intraparenchymal vessels (medullary arteries and veins). The latter investigation will be presented in a future communication.     

Cerebral blood flow dynamics in fetus]

In order to obtain quantitative data concerning the changes of fetal cerebral blood flow occurring in relation to hypoxia and acidemia, we evaluated correlations between fetal blood gases and blood flow velocity waveforms in fetuses. A total of 24 Doppler examinations were carried out to investigate the waveforms of middle cerebral and umbilical arteries in 17 intrauterine growth retardation (IUGR) fetuses. Within 24 hours after blood flow measurements, cordocentesis was performed and umbilical venous blood gases and pH were determined. There was a significant positive correlation between the gestationally adjusted resistance index value [delta SD (RI)] for middle cerebral artery and PO2 or pH, while a negative correlation was noted between the middle cerebral artery delta SD (RI) and PCO2. The umbilical artery delta SD (RI) and pH showed a negative correlation, but there was no correlation between the umbilical artery delta SD (RI) and PCO2 or PCO2. In the presence of partly compensated respiratory acidosis, the delta SD (RI) for middle cerebral artery was still high, while that for umbilical artery did not increase although PO2 was reduced. These findings suggest that blood flow changes in fetal middle cerebral and umbilical arteries are different in IUGR. Middle cerebral artery blood flow may respond directly to changes in PO2. Furthermore, fetal acid-base disorders may modify the relationship between blood flow changes and fetal PCO2.     

Human amniotic epithelial cell transplantation for the repair of injured brachial plexus nerve: evaluation of nerve viscoelastic properties

The transplantation of embryonic stem cells can effectively improve the creeping strength of nerves near an injury site in animals. Amniotic epithelial cells have similar biological properties as embryonic stem cells; therefore, we hypothesized that transplantation of amniotic epithelial cells can repair peripheral nerve injury and recover the creeping strength of the brachial plexus nerve. In the present study, a brachial plexus injury model was established in rabbits using the C6 root avulsion method. A suspension of human amniotic epithelial cells was repeatedly injected over an area 4.0 mm lateral to the cephal and caudal ends of the C6 brachial plexus injury site(1 × 106 cells/mL, 3 μL/injection, 25 injections) immediately after the injury. The results showed that the decrease in stress and increase in strain at 7,200 seconds in the injured rabbit C6 brachial plexus nerve were mitigated by the cell transplantation, restoring the viscoelastic stress relaxation and creep properties of the brachial plexus nerve. The forepaw functions were also significantly improved at 26 weeks after injury. These data indicate that transplantation of human amniotic epithelial cells can effectively restore the mechanical properties of the brachial plexus nerve after injury in rabbits and that viscoelasticity may be an important index for the evaluation of brachial plexus injury in animals.     

环池的显微解剖和临床价值

目的探讨环池的显微解剖及其临床价值。方法利用20具（40侧）尸头标本,动、静脉分别用红蓝色乳胶灌注,模拟颞下入路,了解环池的显微解剖。对环池内的血管和神经走行及毗邻关系进行观察、测量。结果环池内的主要结构脉络膜前动脉、基底静脉、大脑后动脉及滑车神经。主要对基底静脉和滑车神经进行了观察和测量。在外侧膝状体处,基底静脉和大脑后动脉之间的距离为（4．86±1．25）mm。基底静脉大多位于大脑后动脉的上内侧,附于中脑的外侧,直径1．0～4．2mm。基底静脉在中脑外侧面的前缘、外侧膝状体、中脑外侧沟处基底静脉到小脑幕切迹的平均直线距离分别为（9．04±0．68）mm、（4．08±1．25）mm、（6．02±2．01）mm。滑车神经穿入处在后床突后外方（12．88±3．25）mm,在幕中潜行（6．78±1．88）mm。结论熟悉环池内的解剖结构,了解环池中的血管和神经走行,手术的过程中可以更好的保护血管、神经,减少出血及术后并发症。     

去卵巢骨质疏松模型大鼠L4脊椎骨的应力松弛与蠕变☆

背景：去卵巢大鼠脊椎骨会发生哪些应力松弛与蠕变及时间的变化规律？ 目的：观察去卵巢骨质疏松对雌性大鼠承重骨黏弹性特性的影响。 方法：Wistar雌性大鼠44只随机等分为对去卵巢骨质疏松动物模型组和对照组。模型组大鼠于0周摘除卵巢，14周后对大鼠L4椎骨进行应变增加速度为1%/s的应力松弛实验和应力增加速度为0.01 MPa/s的蠕变实验，在7 200 s采集100个数据。 结果与结论：大鼠L4椎骨对照组7 200 s应力松弛量和蠕变量大于模型组(P < 0.05)；同时大鼠L4椎骨应力松弛曲线是以对数关系变化的，蠕变曲线是以指数关系变化的。提示去卵巢骨质疏松大鼠椎骨黏弹性力学特性发生了改变。     

加压螺丝钉内固定股骨颈骨折的蠕变实验

背景：弄清模拟股骨颈骨折单头加压螺丝钉单钉固定,双钉固定,双钉固定植骨后对股骨蠕变力学性质影响对于新型股骨颈骨折内固定器械的研究和股骨颈骨折内固定术式的选择都具有一定的参考价值。 目的：观察加压螺丝钉单钉固定、双钉固定、双钉固定后在骨折区植骨3种方法对股骨颈骨折蠕变特性的影响。 设计、时间及地点：随机对照观察,于2006-08/09在吉林大学力学实验中心完成。 材料：取正常国人急性头部创伤致死的新鲜尸体股骨标本24个,由白求恩医科大学解剖教研室提供。 方法：24个标本随机分为3组,单钉固定组：单钉固定位于模拟骨折面中部;双钉固定组：2枚钉分别位于颈部张力侧;双钉固定植骨组：在双钉固定基础上于骨折线前部垂直骨折线开槽,每组8个标本。以0.5 GPa/min的应力增加速度对标本施加应力,设定时间7 200 s,采集100个实验数据,以回归分析的方法计算归一化蠕变方程。 主要观察指标：各组标本蠕变数据和曲线,蠕变与时间的变化规律。 结果：①蠕变实验结果表明,单钉固定组初始蠕变量为0.493 7%,双钉固定组初始蠕变量为0.402 3%,双钉固定植骨组初始蠕变量为0.382 1%,初始蠕变量大说明其初始位移大,稳定性不好。②单钉固定组7 200 s蠕变量为0.226%,双钉固定组为0.212%,双钉固定植骨组为0.219%。③各组蠕变曲线是以指数关系变化的,在最初600 s变化较快,随时间延长应变缓慢上升,最后进入平衡阶段。 结论：单钉固定、双钉固定和双钉固定植骨3种方法对股骨颈骨折蠕变的影响无明显差异。     

A transcranial Doppler study of blood flow velocity in the middle cerebral arteries performed at rest and during mental activities

While changes in blood velocity in the middle cerebral artery relative to rest were assessed by transcranial Doppler sonography, 70 volunteers with no sign of cerebrovascular disease performed two (left and right middle cerebral artery) series of six cognitive tasks. The tasks are assumed to be processed predominantly by either the left (verbal and mathematical tests performed aloud) or the right hemisphere (dot/distance estimation, spatial perception, and face recognition performed silently). All tasks were shown to increase middle cerebral artery blood flow velocity on both sides, by 1.6-10.6%. After an initial maximum at approximately 8 seconds, velocity decreased then increased again. A steady state was reached after approximately 24-42 seconds. The initial minimum during the following rest phase was reached some seconds later, followed by a slow increase to the reference rest steady state. A difference according to side could be determined only during the three right-hemispheric tasks (right greater than left, 2.5-2.9%). Left-handedness/ambidexterity, familial sinistrality, and profession seemed to have no influence on the results. The middle cerebral artery blood flow velocity increase on both sides was higher in women than in men during the dot/distance estimation and was also higher bilaterally in older than in younger subjects during the dot/distance and the spatial perception tasks. Habituation in performing the tasks was an important factor associated with a decrease of blood flow velocity, especially in the right middle cerebral artery. The habituation more pronounced on the right side possibly reflects the role of the right hemisphere in attention and arousal. The absolute blood velocities at rest decreased bilaterally with age.     

Human umbilical cord blood-derived stem cells and brain-derived neurotrophic factor protect injured optic nerve：viscoelasticity characterization

The optic nerve is a viscoelastic solid-like biomaterial.Its normal stress relaxation and creep properties enable the nerve to resist constant strain and protect it from injury.We hypothesized that stress relaxation and creep properties of the optic nerve change after injury.Moreover,human brain-derived neurotrophic factor or umbilical cord blood-derived stem cells may restore these changes to normal.To validate this hypothesis,a rabbit model of optic nerve injury was established using a clamp approach.At 7 days after injury,the vitreous body received a one-time injection of 50 μg human brain-derived neurotrophic factor or 1 × 106 human umbilical cord blood-derived stem cells.At 30 days after injury,stress relaxation and creep properties of the optic nerve that received treatment had recovered greatly,with pathological changes in the injured optic nerve also noticeably improved.These results suggest that human brain-derived neurotrophic factor or umbilical cord blood-derived stem cell intervention promotes viscoelasticity recovery of injured optic nerves,and thereby contributes to nerve recovery.     

Comparison of viscoelasticity between normal human sciatic nerve and amniotic membrane

Sciatic nerve tissue was obtained from the gluteus maximus muscle segment of normal human cadavers and amniotic membrane tissue was obtained from healthy human puerperant placentas.Both tissues were analyzed for their stress relaxation and creep properties to determine suitability for transplantation applications.Human amniotic membrane and sciatic nerve tissues had similar tendencies for stress relaxation and creep properties.The stress value of the amniotic membrane stress relaxation group decreased to a greater extent compared with the sciatic nerve stress relaxation group.Similarly,the stress value of the amniotic membrane creep group increased to a greater extent compared with the sciatic nerve creep group.The stress relaxation curve for human amniotic membrane and sciatic nerve showed a logarithm correlation,while the creep curve showed an exponential correlation.These data indicate that amniotic membrane tissue has better stress relaxation and creep properties compared with sciatic nerve tissue.     

Distribution and differentiation of bone marrow-derived mesenchymal stem cells in vivo after intraperitoneal and tail vein injection into rats in the recovery phase of stroke Which path is better?

BACKGROUND:Stereotactic injection(striatum or lateral ventricle)and vascular injection(tail vein or carotid artery)are now often used in cellular therapy for cerebral infarction.Stereotactic injection can accurately deliver cells to the infarct area,but requires a stereotactic device and causes secondary trauma;vascular injection is easy and better for host neurological deficit recovery,but can cause thrombosis.OBJECTIVE: To compare the therapeutic potential of adult bone marrow-derived mesenchymal stem cells(BMSCs)transplantation by intraperitoneal versus intravenous administration to cerebral ischemic rats.DESIGN,TIME AND SETTING: A randomized controlled animal experiment was performed at the Cell Room and Pathology Laboratory,Brain Hospital Affiliated to Nanjing Medical University from November 2007 to September 2008.MATERIALS: BMSCs were derived from 20 healthy Sprague-Dawley rats aged 4-6 weeks.METHODS: Forty-five adult middle cerebral artery occlusion(MCAO)rats were randomly divided into control,intravenous and intraperitoneal injection groups,with 15 rats in each group.At 21 bromodeoxyuridine(BrdU)via intravenous or intraperitoneal injection.MAIN OUTCOME MEASURES: Angiogenin expression and survival of transplanted cells were measured by immunohistochemical staining of brain tissue in infarction hemisphere at 7,14 or 21 days after BMSC transplantation.Co-expression of BrdU/microtubule-associated protein 2 or BrdU/glial fibrillary acidic protein was observed by double-labeled immunofluorescence of cerebral cortex.Evaluation of nerve function using the neurological injury severity score and the adhesion-removal test was performed on the 1st and 21st day before and after MCAO,and at 3,7,14 or 21 days after BMSCs treatment.RESULTS: Angiogenin-positive new vessels were distributed in the bilateral striatum,hippocampus and cerebral cortex of each group of rats at each time point,most markedly in the intravenous injection group.There were significantly more BrdU-positive cells in the intravenous injection group than in the intraperitoneal injection group(P < 0.01).Co-expression of BrdU/ microtubule-associated protein 2 or BrdU/glial fibrillary acidic protein were almost only seen in theintravenous group by fluorescence microscopy.After transplantation,BMSCs significantly restored nerve function in rats,particularly in the intravenous injection group.CONCLUSION: BMSCs were able to enter brain tissue via the tail vein or peritoneal injection and improve neurological function by promoting the regeneration of nerves and blood vessels in vivo,more effectively after intravenous than intraperitoneal injection.     

大鼠局灶性脑缺血后受累动脉调节功能受损

目的 研究脑缺血对受累动脉调节功能的影响,探讨缺血再灌注损伤发生的可能机制.方法 线栓法制作大鼠大脑中动脉梗死模型,2 h后取受累侧大脑中动脉游离血管段,测量压力和血管活性物质诱发的动脉直径变化,据此计算出膨胀性、肌源性张力及对5-羟色胺和乙酰胆碱的反应性,与对照组对比.结果 低压区,缺血动脉肌源性张力增加[40mm Hg(1 mm Hg=0.133 kPa)时,19.3%±0.4%与10.0%±0.2%,t=20.568,P=0.000],直径缩小(F=9.572,P=0.009);高压区肌源性张力下降(120 mm Hg时,12.0%±0.2%与21.8%±0.4%,t=-23.575,P=0.000),动脉易膨胀,直径增大;生理压力区,肌源性反应变化不明显(80 mm Hg时,18.7%±0.4%与18.3%±0.3%,t=0.635,P=0.537).缺血后动脉对5-羟色胺和乙酰胆碱反应性下降.结论 脑缺血可引起受累动脉调节功能0下降,动脉再通后易出现缺血区的过度灌注,造成缺血再灌注损伤.     

Evidence for a therapeutic effect of Braintone on ischemic brain damage

This study used a novel combination of in vivo and in vitro experiments to show that Braintone had neuroprotective effects and clarified the molecular mechanisms underlying its efficacy. The Chinese herbal extract Braintone is composed of Radix Rhodiolase Essence, Radix Notoginseng Essence, Fofium Ginkgo Essence and Rhizoma Chuanxiong. In vivo experiments showed that cerebral infarction volume was reduced, hemispheric water content decreased, and neurological deficits were alleviated in a rat model of permanent middle cerebral artery occlusion after administration of 87.5, 175 or 350 mg/kg Braintone for 7 consecutive days. Western blot analysis showed that Braintone enhanced the expression of hypoxia-inducible factor la, heme oxygenase-1 and vascular endothe- lial growth factor in the ischemic cortex of these rats. The 350 mg/kg dose of Braintone produced the most dramatic effects. For the in vitro experiments, prior to oxygen-glucose deprivation, rats were intragastrically injected with 440, 880 or 1 760 mg/kg Braintone to prepare a Braintone-co ntaining serum, which was used to pre-treat human umbilical vein endothelial cells for 24 hours. Human umbilical vein endothelial cell injury was alleviated with this pre-treatment. Western blot and real-time PCR analysis showed that the Braintone-containing serum increased the levels of hy- poxia-inducible factor la mRNA and protein, heine oxygenase-1 protein and vascular endothelial growth factor mRNA in oxygen-glucose deprived human umbilical vein endothelial cells. The 1 760 mg/kg dose produced the greatest increases in expression. Collectively, these experimental findings suggest that Braintone has neuroprotective effects on ischemia-induced brain damage via the up-regulation of hypoxia-inducible factor la, heme oxygenase-1 and vascular endothelial growth factor expression in vascular endothelial cells.     

Evidence of a cerebrovascular postarteriole windkessel with delayed compliance.

A pronounced temporal mismatch was observed between the responses of relative cerebral blood volume (rCBV) measured by magnetic resonance imaging and relative cerebral blood flow measured by laser-Doppler flowmetry in rat somatosensory cortex after electrical forepaw stimulation. The increase of relative cerebral blood flow after stimulus onset and decrease after stimulus cessation were accurately described with a single exponential time constant of 2.4 +/- 0.8 seconds. In contrast, rCBV exhibited two distinct and nearly sequential processes after both onset and cessation of stimulation. A rapid change of rCBV (1.5 +/- 0.8 seconds) occurring immediately after onset and cessation was not statistically different from the time constant for relative cerebral blood flow. However, a slow phase of increase (onset) and decrease (cessation) with an exponential time constant of 14 +/- 13 seconds began approximately 8 seconds after the rapid phase of CBV change. A modified windkessel model was developed to describe the temporal evolution of rCBV as a rapid elastic response of capillaries and veins followed by slow venous relaxation of stress. Venous delayed compliance was suggested as the mechanism for the poststimulus undershoot in blood oxygen-sensitive magnetic resonance imaging signal that has been observed in this animal model and in human data.     

Regulation of Rat Sympathetic Nerve Density by Target Tissues and NGF in Maturity and Old Age

Previous studies in our laboratory using a transplantation model have shown that target tissues of some autonomic neurons, including cerebral blood vessels, exert a controlling influence on nerve fibre loss in old age. The present study was undertaken in order to discover whether the influence of targets extends to controlling age changes in specific populations of nerves. In old rats, we have demonstrated a significant decrease of -50% in the sympathetic innervation of middle cerebral arteries, using tyrosine hydroxylase-like immunoreactivity. Following transplantation, tyrosine hydroxylase-like immunoreactive nerve density on both young and old implanted middle cerebral arteries mirrored the nerve densities seen in normal, non-transplanted vessels. Furthermore, implanted tissue from old donors became reinnervated with a nerve density -50% less than that of young implanted vessels. Treatment of transplants with nerve growth factor, however, was able to reverse these age changes and restore the sympathetic innervation of aged middle cerebral arteries to levels above those seen in young middle cerebral arteries. These results suggest that the pattern and density of sympathetic innervation that the middle cerebral artery receives is determined by the target rather than by the neurons supplying the tissue. The ability of nerve growth factor to induce regrowth in sympathetic neurons innervating ageing target tissues implies that age-related neuronal atrophy may be due to reduced synthesis or availability of target-derived neurotrophic factors.     

骨性关节炎动物模型内侧副韧带的应力松弛☆

背景：韧带和其他生物软组织一样,具有黏弹性特性,其应力松弛和蠕变黏弹性特性是为适应人的生理功能需要而存在的。研究说明骨性关节炎对韧带力学性能具有一定影响。 目的：比较正常和骨性关节炎动物模型内侧副韧带的应力松弛流变特性,确定骨性关节炎对内侧副韧带应力松弛特性的影响。 方法：以闭合关节刻痕法复制骨性关节炎动物模型,取正常和骨性关节炎动物模型大鼠膝关节内侧副韧带各10个试样,进行应力松弛实验。应力松弛实验的应变增加速度为5%/s。设定实验时间为7 200 s,采集100个数据,观察应力松弛数据和曲线、应力与时间的变化规律,以一元线性回归分析的方法处理实验数据。 结果与结论：正常组和病态组试样应力松弛最初600 s变化较快,之后应力缓慢下降,正常组7 200 s应力松弛量0.47 MPa,病态组7 200 s应力松弛量0.29 MPa。模型组7 200 s应力松弛量显著低于正常组(P < 0.05),且应力松弛曲线是以对数关系变化的。说明骨性关节炎时可以使膝关节对内侧副韧带应力松弛量降低,对膝关节应力松弛特性具有一定影响。