吗啡诱发条件性位置偏爱激活时大鼠伏隔核前额叶皮层p-CREB、c-Fos的变化

目的 探讨吗啡诱发条件性位置偏爱激活时大鼠伏隔核、前额叶皮层磷酸化cAMP反应元件结合蛋白(phospho-cAMP response element binding protein,p-CREB)和c-Fos表达的变化.方法 以剂量递增法连续皮下注射(SC)吗啡6d建立大鼠条件性位置偏爱(conditioned place preference,CPP)模型,第7天用生理盐水替代吗啡训练大鼠10d,使形成的cPP逐渐消退,单次SC 4mg·kg-1吗啡激发已消退的CPP.采用免疫组化技术测定吗啡激发CPP重现时大鼠伏隔核、前额叶皮层p-CREB和c-Fos的变化.结果 (1)吗啡可使大鼠产生CPP效应,吗啡4mg·kg-1可使已消失的CPP效应激活;(2)与对照组相比吗啡诱发的CPP激活时大鼠伏隔核、前额叶皮层p-CREB(161.18±5.37,179.75±7.68)和c-Fos(176.63±8.42,185.11±5.61)的表达增加,与NS组比较差异有显著性(P＜0.05).结论 伏隔核、前额叶皮层p-CREB和c-Fos蛋白表达参与了吗啡的CPP重现.     

维生素C、氢化可的松、维拉帕米合用防治大鼠小肠缺血再灌注损伤

目的　探讨维生素 C、氢化可的松、维拉帕米三药联合应用对小肠缺血再灌注损伤的防治作用及其起作用的机制 ,为临床用药提供参考 .方法　采用大鼠常温小肠缺血 6 0min-再灌注 (I/R)模型 ,治疗组动物于再灌注前 1 0 min尾静脉依次给予维生素 C (2 0 0 mg· kg- 1)、维拉帕米 (0 .5 2 mg·kg- 1)和氢化可的松 (1 0 .42 mg· kg- 1) ,开夹后立即再次注入上述剂量维生素 C和维拉帕米 .观测动物血压、微血管通透性、组织水含量及再灌注 1 2 0 min死亡率等指标 .结果　治疗组再灌注 1 2 0 min死亡率为 0 ,而 I/R组死亡率为 1 0 0 % ,两组有显著差异 (P<0 .0 5 ) ,治疗组死亡率明显降低 ;至开夹 90min和 1 2 0 min时 I/R组血压几乎为 0 ,治疗组仍保持在较高水平且趋于稳定 ,与 I/R组有显著差异 (P<0 .0 1 ) ;三药合用使组织水肿程度显著减轻 (P<0 .0 1 ) ,组织微血管通透性有所降低 (P<0 .0 5 ) .结论　维生素 C、维拉帕米、氢化可的松三种药物联合应用可明显减轻大鼠小肠缺血 /再灌注损伤 ,这与维生素 C的自由基清除作用、维拉帕米的钙拮抗作用以及氢化可的松的炎症反应抑制作用有关     

染料木素胶囊对骨质疏松症大鼠骨质代谢影响的比较研究

目的　通过对骨质疏松症大鼠股骨生物力学和骨密度的比较研究 ,探讨染料木素胶囊对其骨质代谢的影响。方法　SD雌性大鼠 2 90只 ,随机分为正常对照组、模型组、骨疏康组 (5g·kg- 1 )、尼尔雌醇组 (1 5mg·kg- 1 )、染料木素大剂量 (18mg·kg- 1 )、中剂量 (9mg·kg- 1 )、小剂量 (4 5mg·kg- 1 )剂量组。模型大鼠切除双侧卵巢 (正常对照组行假手术 ) ,诱发雌激素缺乏性大鼠骨质疏松症。术后第 8天开始给药并分别于不同时间点杀死大鼠 ,取双侧股骨、胫骨和腰椎L2 - 4,进行相关指标的测定。结果　①尼尔雌醇和染料木素中剂量组可抑制动物体重的增长 ,也可使左股骨重、左胫骨长和左胫骨重明显增加 (P <0 0 1或P <0 0 5 ) ;②各组大鼠的股骨、胫骨和腰椎骨密度均有不同程度的改善 ,且染料木素在 4 5mg·kg- 1 、9mg·kg- 1 时比尼尔雌醇作用更显著 (P <0 0 5或P <0 0 1) ;③染料木素在 4 5mg·kg- 1 时可显著改善去势大鼠股骨的最大载荷 ,在 18mg·kg- 1 时可改善去势大鼠股骨的最大桡度 ,各剂量组均可改善去势大鼠股骨的弹性载荷 ,在 9mg·kg- 1 时可改善去势大鼠股骨的弹性桡度。结论　染料木素在 4 5～ 9mg·kg- 1 时对骨质疏松症大鼠的股骨生物力学和骨密度有显著的改善作用。     

电针抑制大鼠吗啡条件性位置偏爱

目的 :观察不同频率电针刺激能否抑制大鼠吗啡条件性位置偏爱 (conditionedplacepreference ,CPP)的表达。方法 :采用计算机自动控制的三室迷宫CPP系统 ,第 1天测试天然偏爱 ;第 2至 5天进行条件训练 (吗啡 4mg·kg-1,i.p ,对照组给予等量的生理盐水 ) ;第 6天在无药状态下观察大鼠在伴药盒的停留时间。于CPP检测后2 4h ,分别给予大鼠 2Hz或 10 0Hz的电针刺激 ,每天 1次 ,连续 3天 ,最后一次电针结束后 2 4h测定大鼠在伴药盒停留时间。结果 :实验组大鼠在伴药盒的偏爱分数明显高于对照组。 2Hz及 10 0Hz电针均能明显降低CPP大鼠在原伴药盒的偏爱分数。结论 :多次 2Hz及 10 0Hz电针均能抑制大鼠吗啡CPP表达 ,两种频率的抑制效应差异无显著性。     

左旋延胡索乙素对吗啡条件性位置偏爱大鼠伏核NR1蛋白表达的影响

目的研究左旋延胡索乙素(l-tetrahydropalmatine,l-THP)对吗啡诱发条件性位置偏爱(conditioned place preference,CPP)大鼠伏核(nucleus accumbens,NAc)中N-甲基-D-天冬氨酸受体NR1亚基(NR1)表达改变的影响。方法大鼠随机分组,即正常对照组、模型CPP组、生理盐水治疗组及l-THP低(0.94 mg/kg)、中(1.88 mg/kg)和高(3.76 mg/kg)治疗组。正常对照组皮下注射等量生理盐水外,剩余各组大鼠采用颈背部皮下剂量递增法注射吗啡(起始剂量10 mg/kg,每天递增10 mg/kg,至注射10 d时为100 mg/kg),经CPP训练10 d,末次训练后48 h进行CPP检测确认CPP模型成功。各治疗组大鼠灌胃给药,每天1次,连续治疗6 d后进行CPP检测,之后处死大鼠并采用脑立体定位仪取大鼠NAc脑组织,利用Western Blot方法检测NR1基因的蛋白表达。结果经CCP检测,模型组大鼠在白箱(吗啡伴药箱)停留时间,与生理盐水组比较明显延长(P<0.05),而经l-THP 1.88和3.76 mg/kg治疗后,停留时间恢复至正常对照组水平。Western Blot检测到CPP大鼠NAc核团NR1的蛋白表达较正常对照组显著增加(P<0.01),l-THP 1.88和3.76 mg/kg治疗后,NR1蛋白表达被逆转。结论在大鼠吗啡精神依赖过程中l-THP可显著抑制NAc核团中NR1蛋白表达的增加,这一作用可能是l-THP加速大鼠吗啡CPP效应消退的机制之一。     

中枢和外周注射东莨菪碱对吗啡条件性位置偏爱的影响

为探讨脑内胆碱能神经系统与大鼠的吗啡条件性位置偏爱行为的关系，作者用体重200～250g雄性SD大鼠建立吗啡条件性位置偏爱模型。模型动物随机分为4组：①侧脑室注射生理盐水组，②侧脑室注射东莨碱组，③腹腔注射生理盐水组，④腹腔注射东莨碱组．测试前30min，给第2组侧脑室注入20μg东莨碱，对照组给予等量生理盐水。结果前者的吗啡条件性位置偏爱效应减弱（P＜0．05）．腹腔注射0．5mg／kg东莨碱对吗啡条件性位置偏爱效应影响不著。结果提示，脑内胆碱能神经系统参与吗啡偏爱效应的形成，东莨碱可能通过阻断脑内胆碱能M受体抑制了吗啡条件性位置偏爱行为。     

青龄大鼠和成龄大鼠在吗啡条件性位置偏爱和行为敏感化效应上的差异

目的 考察青龄大鼠在吗啡奖赏效应和行为激活效应上是否比成龄大鼠更加敏感.方法 使用条件化位置偏爱程序检验吗啡奖赏效应和行为敏感化效应,青龄雄性大鼠(出生后35d)和成龄雄性大鼠(出生后67d)每天接受盐水或吗啡(3mg/kg)注射,进行6d的位置条件化训练,同时记录条件化训练期间大鼠在伴药箱的水平运动量,训练结束24h后对条件性位置偏爱效应进行检测.结果 青龄大鼠没有形成吗啡条件性位置偏爱效应[盐水组(20.89±31.14)s,吗啡组(90.75±27.91)s,P=0.15];成龄大鼠形成了吗啡条件性位置偏爱效应[盐水组(31.5±41.24)s,吗啡组(266.13±32.26)s,P<0.01];成龄大鼠的吗啡条件性位置偏爱效应显著高于青龄大鼠(p<0.01).青龄吗啡组大鼠d3～d6的水平运动量均显著高于dl(P<0.05或P<0.01),成龄吗啡组大鼠d2～d6的水平运动量均显著高于d1(P<0.05或P<0.01);对吗啡给药大鼠进行二因素重复测量方差分析表明:年龄主效应不显著[F_(1,14)=0.33,JP=0.57],年龄×处理交互作用不显著[F_(5,70)=0.85,P=0.52].结论 青龄大鼠对吗啡的奖赏效应不如成龄大鼠敏感,但与成龄大鼠有着类似的行为敏感化效应.     

染料木素对维甲酸模型大鼠血生化指标和骨密度的作用

目的 :探讨染料木素对维甲酸所致骨质疏松模型大鼠的影响 .方法 :取SD雄性大鼠 2 5 6只 ,随机分为正常对照组、模型组、骨疏康组 (5g·kg-1)、染料木素大、中、小剂量组(18,9,4 .5mg·kg-1) .给予维甲酸 70mg·kg-1·d-1灌胃 2wk(正常对照组除外 ) ,分别于不同时间从各组取 8只大鼠对体质量、血生化指标和骨密度等进行测定 .结果 :染料木素①可增加维甲酸模型大鼠的左股骨质量、左胫骨质量 (P <0 .0 5或P <0 .0 1) ;②使模型大鼠的血清Ca ,P ,Mg,CT水平明显降低 ,BGP ,ALP水平升高 ,与模型组有显著差异 (P <0 .0 5或P <0 .0 1) ;③在 4 .5mg·kg-1,9mg·kg-1时可明显增强模型大鼠的股骨、胫骨和腰椎L2 -4的骨密度 (P <0 .0 5或P <0 .0 1) .结论 :染料木素可明显改善维甲酸模型大鼠的骨密度和血生化指标 ,对骨质疏松有较好的疗效     

中药大明胶囊对2型糖尿病大鼠空腹血糖作用的研究

目的　探讨大明胶囊对 2型糖尿病大鼠空腹血糖的影响。方法　建立 2型糖尿病大鼠模型 ,筛选空腹血糖值大于 16 .7mmol·L- 1 的大鼠随机分组 :大明胶囊大 (187.5mg·kg- 1 ·d- 1 )、中 (93.8mg·kg- 1 ·d- 1 )、小 (46 .9mg·kg- 1 ·d- 1 )剂量组、糖尿病模型组、苯乙双胍 (75mg·kg- 1 ·d- 1 )组 ,连续用药 14d ,用葡萄糖氧化酶法测空腹血糖值 ,同时对大明胶囊治疗前后 2型糖尿病大鼠 2 4h进食量、饮水量、体重及甘油三酯进行测定。结果　 2型糖尿病大鼠经大明胶囊灌胃给药后空腹血糖值与模型组相比有明显降低 (P <0 .0 5 ) ,并且饮水量、进食量及TG与模型组相比明显下降 (P <0 .0 5 )。结论　大明胶囊对 2型糖尿病大鼠有明显的降低空腹血糖作用 ,并且可以改善糖尿病的症状。     

氢化可的松"虚证"模型大鼠的心率变异性研究

目的研究氢化可的松"虚证"模型大鼠的心率变异性(HRV)的变化特征,从"虚证"动物模型,探讨中医证的客观化.方法将36只SD大鼠随机分为正常对照组(对照组)、氢化可的松组(模型组)、氢化可的松+桂附地黄丸组(加药组),模型组和加药组按50 mg·kg-1·d-1氢化可的松剂量灌胃,连续12 d,加药组同时灌桂附地黄丸,模型组予等同剂量的生理盐水.从第13天起,停用氢化可的松,换成等剂量的生理盐水,加药组桂附地黄丸液继续灌胃,再连续12 d.分别测定上述各组第12天、第24天后的HRV.结果第12天后,与对照组比较,模型组TP、VLF、LF、HF、SD均下降,但无统计学差异,而HR明显升高(P＜0.01);与对照组、模型组比较,加药组TP、VLF、LF、HF、SD均明显降低(P＜0.05或P＜0.01).第24天后,与对照组比较,模型组TP、LF、SD显著增加(P＜0.05)加药组HRV各参数均无统计学意义(P＞0.05).结论氢化可的松制备的"虚证"模型大鼠HRV有明显改变,表明交感神经和副交感神经功能受损.HRV检测对"虚证"动物有一定的特征性表现.     

Value of D-Dimers in patients with acute aortic dissection

Objective: To evaluatel the value of D-dimers in patients with acute aortic dissection (AAD). Methods: This study consisted of 16 patients with AAD and 27 non-AAD patients. Serum D-dimets were measured by Sta-Liatest D-DI immunoturbidimetric assay. Results: D-dimer level was higher (P ＜ 0.001) in patients with AAD(7.91 ± 5.52 μg/ml) than that in non- AAD group(1.57±1.24 μg/ml). D-dimer was positive (＞0.4 μg/ml) in all patients with AAD and in 10 control group patients (37%). Among patients with acute AAD, D-dimers tended to be higher in Stanford A than in Stanford B (8.67 ± 4.31 μg/ml vs. 3.24±1.27 μg/ml, P ＜0.01). D-dimer values tended to be higher in more extended disease(3.84 ± 1.65 μg/ml, 8.57 ± 3.58 μg/ml and 11.87 ± 5.69 μg/ml in thoracic aorta, thoracic and abdominal aorta, thoracic and abdominal aorta and iliacal arteries, respectively, P ＜ 0.05 for both 8.57 ± 3.58 and 11.87 ± 5.69 vs. 3.84 ± 1.65 ). Including the control group into the analysis, we found a sensitivity of 100%, a negative predictive value of 100%, and a specificity of 66% and a positive predictive value of 64% for D-dimer in diagnosis of AAD in our patients with suspected AAD. Conclusion: D-dimer was elevated in patients with AAD. A negative D-dimer test result could be useful in excluding AAD.     

Research of combined liver-kidney transplantation model in rats

Objective： To set up a simple and reliable rat model of combined liver-kidney transplantation. Methods： SD rats served as both donors and recipients. 4℃ sodium lactate Ringer＇s was infused from portal veins to donated livers,and from abdominal aorta to donated kidneys, respectively. Anastomosis of the portal vein and the inferior vena cava （IVC） inferior to the right kidney between the graft and the recipient was performed by a double cuff method, then the superior hepatic vena cava with suture. A patch of donated renal artery was anastomosed to the recipient abdominal aorta. The urethra and bile duct were reconstructed with a simple inside bracket. Results： Among 65 cases of combined liver-kidney transplantation, the success rate in the late 40 cases was 77.5%. The function of the grafted liver and kidney remained normal. Conclusion： This rat model of combined liver-kidney transplantation can be established in common laboratory conditions with high success rate and meet the needs of renal transplantation experiment.     

BLOOD PRESSURE CHANGE WITH AGE IN SALT-SENSITIVE TEENAGERS

Objective To observe blood pressure change with age in salt-sensitive teenagers whose salt sensitivity were determined by repeated testing.Methods Salt sensitivity was determined through intravenous infusion of normal saline combined with volume-depletion by oral diuretic furosemide in 55 teenagers. After five years, salt sensitivity was re-examined and subject blood pressure was followed up. Blood pressure changes in salt-sensitive teenagers were compared to that of non-salt sensitive teenagers over five years.Results After 5 years, the repetition rate of salt sensitivity determined by intravenous saline loading is 92.7%. In teenagers with salt sensitivity on the baseline, both the systolic blood pressure increments and increment rates were much higher than non-salt sensitive teenagers (12.7±12.1 mmHg vs. 2.8±5.2 mmHg, P＜ 0.01; 12.2%± 12.0% vs. 2.5% ±4.4%, P＜ 0.001,respectively). There was a similar trend for diastolic blood pressure (8.4 ± 6.4 mmHg vs. 3.7 ± 6.4 mmHg, P = 0.052; 13.2% ±10.6 % vs. 6.8%± 10.1%, P = 0.053, respectively).Conclusions Salt sensitivity determined by intravenous saline loading showed good reproducibility. Blood pressure increments with age were much higher in salt-sensitive teenagers than non-salt sensitive teenagers, especially in terms of systolic blood pressure.     

安心颗粒对急诊经皮冠状动脉介入术后生活质量影响的研究

目的：评价使用安心颗粒对急诊经皮冠状动脉介入术（PPCI）术后生活质量的影响.方法：将160例接受PPCI的急性ST段抬高型心肌梗死患者随机分为安心颗粒组（术前顿服安心颗粒8.8g,术后安心颗粒4.4 g/次,每日2次）和对照组（仅接受基础药物治疗）.所有患者均服用阿司匹林、氯吡格雷和阿托伐他汀.分别在入院时、出院前1d、出院后180 d时,应用心肌梗死多维度量表（MIDAS）、中文版SF-36评价量表对患者生活质量评分.并观察术后30 d以内的出血并发症、血小板减少症发生情况.结果：入院时和出院前1d,两组患者的心肌梗死MIDAS、SF-36量表评分比较无差异（P＞0.05）;出院后180 d时,与对照组比较,安心颗粒组MIDAS、SF-36评分明显减低（P＜0.05）;组内与入院时比较,两组出院前1d、出院后180 d时,MIDAS、SF-36评分均降低（P＜0.05）.两组患者在随访期间均无大量出血、少量出血、重度和极重度血小板减少症发生,安心颗粒组有4例、对照组有7例发生不明显出血（P＞0.05）.两组发生轻度血小板减少症的患者数比较无差异（P＞0.05）.结论：PPCI使用安心颗粒,能改善急性ST段抬高型心肌梗死患者的生活质量,且不增加出血风险.     

The comparative studies of the influences of Urapidil and Nicardipine on sino-atrial node function, atrio-ventricular node function and hemodynamics

Objective:To investigate the influences of urapidil and nicardipine on rabbit sinus function,atrio-ventricular node function and hemodynamics.Methods:Thirty-two Angora's rabbits were selected and randomly divided into four groups.U1 group:urapidil 0.25 mg/kg;U2 group:urapidil 0.5 mg/kg;N1 group:nicardipine 10 μg/kg;N2 group:nicardipine 20 μg/kg.All these medicine were administrated within 30 seconds.Measurements were taken before and after the administration of urapidil or nicardipine for the following data:mean blood pressure(MAP),heart rate(HR),sino-atrial conduction time(SACT),maximal sinoatrial recovery time(SNRTmax)corrected sinus node recovery time(CSNRT),index of sinus node recovery time(SNRTI),Wenckebach A-V conduction frequency (WB),and P-R interval.Results:Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine.No significant changes could be found in the rest of the parameters.Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group(P＜0.01);the MAP decreased(P＜0.01)and the HR increased drastically(P＜0.01).Conclusions:Neither urapidil(0.25 mg/kg,0.5 mg/kg)nor nicardipine(10μg/kg,20μg/kg)has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function.Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.     

Expression of OPGmRNA and ODFmRNA in the patients of hip fracture due to osteoporosis

Objective：To investigate the gene expression of osteoprotegerin（OPG） and osteoclast differentiation factor（ODF） in the bone tissue of patients with hip fracture due to osteoporosis. Methods：OPGmRNA and ODFmRNA in the bone tissue in 50 cases of osteoporosis sufferers（over 50 years old） with hip fracture（Observer Group） and 30 cases of hip facture sufferers with no osteoporosis（Control group） were analyzed with the Semi-Quantitative RT-PCR method. Results：The mRNA expressed of ODF, OPG were both high in the patients with hip fracture. In the control group, the expression of OPG mRNA was observed, while the expression of ODF mRNA was very slight. Conclusion：Aged patients contained all signals including OPG, ODF that are essential for inducing osteoclastogenesis and promoting bone resorption.     

The clinicopathological and immuohistochemical analysis of solid-pseudopapillary tumor of the pancreas： report of 9 cases

Objective：To investigate the clinical features, pathological characteristics and immunophenotype of solid-pseudopapillary tumor of the pancreas（SPTP）. Methods：Nine surgically treated cases of SPTP were retrospectively reviewed. Hematoxylin and Eosin（HE） staining and immunohistochemical staining were used to analyze all cases, and the general clinical data was collected. Results：Six patients were asymptomatic except for a palpable mass. Two patients complained of vague-epigastric pain. One patient appeared jaundice. The tumor was encapsulated and solid tissues alternately with cystic tissues. Histologically, the histological structure of solid portion was pseudopapillary with a fibrovascular core. Tumor cells were uniform and medium-sized which were arranged in sheets ets or nests or pseudopapillary patterns. Immunohistochemical studies demonstrated that SPTP proved positive in vimentin（9/9 cases）, AAT（9/9 cases）, NSE（9/9 cases）, ACT（7/9 cases）, CK20（2/9 cases）, CgA（1/9 cases）, S-100（3/gcases）, PR（4/gcases）, Syn（3/9 cases） and CD56（5/9cases）, negative in CEA and ER. Conclusion：SPTP is a tumor predominantly occurring in young women frequently without special symptoms. This tumor has various characteristical histological patterns with different immunophenotype.     

Dynamic Changes in Serum Estradiol and Progesterone levels in Patients of Premenstrual Syndrome with Adverse Flow of Liver-qi

Objective:To probe into the influence of changes of ovarian hormones on the pathogenesis of the specific sub-type premenstrual syndrome(PMS)and reveal partial microcosmic mechanisms of adverse flow of liver-qi.Methods:Estradiol(E2)and progesterone(P)levels in serum were determined at different phases of menstrual cycle by radioimmunoassay.Results:In the group of PMS with adverse flow of liver-qi.the secretive peak value Of E2 and P at the follicular phase significantly decreased,and the secretive peak value at the luteal phase did not come into being.Conclusions:Low E2 and P secretive peak at the follicular phase and absence of secretive peak at the luteal phase is one of the microcosmic mechanisms of PMS with adverse flow of liver-qi.One of the pathophysiologic mechanisms of specific sub-type PMS is probably the continuous low level of E2and P.     

Real-time Three-dimensional Echocardiography in Assessment of Left Ventricular and Right Ventricular Volumes

Real-time three-dimensional echocardiography (RT3DE)is a new ultrasound technique that enables dynamic threedimensional visualization and quantification of the heart in real time. Investigation of feasibility and methodology of RT3DE in determining left ventricular (LV) and right ventricular (RV) volumes, RT3DE was performed in 35 normal adults using Philips SONOS 7500 system with a 2-4 MHz matrix array transducer. The 60°×60° "pyramid" volume database was obtained and analyzed on a TomTec echo workstation. Both LV and RV volumes were calculated with four 3DE methods (i.e. apical 2, 4, 8, and 16-plane) through manually tracing ventricular endocardial borders in end diastole and end systole. Stroke volumes were then calculated. LV volume was also measured by 2DE Simpson's rule using GE VIVID 7 ultrasound machine.     

SCREENING FOR A 21-CHROMOSOME ABNORMALITY IN PREIMPLANTED EMBRYOS OF ELDERLY WOMEN

Increasing maternal age is the only etiological factor unequivocally linked to Down's syndrome in humans. The occurrence rate of newborns with Down's syndrome is about 1/220 in women over 35 years old. However, the occurrence rate in embryos fertilized in vitro, of the elder woman is unclear. Using FISH we screened the number of chromosome 21 in preimplanted embryos of 5 elderly women (average age, 38.4 years) to study the feasibility and necessity of screening trisomy 21 in embryos in patients over 35 years old at the in vitro fertilization (IVF) center.