兔急性肺血栓栓塞及溶栓后TXA2?PGI2及ET-1水平的变化与血流动力学相关性研究

目的:探讨兔急性肺动脉血栓栓塞时血清炎症因子血栓素A2(TXA2)、前列环素(PGI2)和肺血管内皮、支气管和肺泡上皮等部位内皮素1(ET-1)变化和血流动力学指标变化及尿激酶(UK)溶栓的影响。方法:24只大耳白兔随机分为对照组、急性肺栓塞(acute pulmonary thromboembolism,APTE)模型组、尿激酶(UK)治疗组,每组8只。采用自体血栓回输法建立动物模型。常规于造模前、造模后1、2、4、8h放免法测定血清TXA2、PGI2,漂浮导管监测血流动力学指标,最后免疫组化法检测肺血管内皮、支气管和肺泡上皮各部位ET-1的表达水平。结果:①放免法测定结果:对照组各时间点无显著差异。模型组1h升高,4h达高峰,其后开始降低,1、2、4h点与对照组比较都有统计学意义(P<0.01)。UK组1h升高,2h达高峰,4h后开始下降,UK组高峰值较模型组低,1、2、4h UK组与模型组两者有统计学意义(P<0.01)。各组术前和8h无统计学差异(P>0.05);②血流动力学监测结果:对照组各时间点肺动脉平均压(PAMP)、中心静脉压(CVP)都无明显变化,模型组及UK组PAMP、CVP栓塞后立即升高...     

实验性大鼠肺血栓栓塞血浆TXA_2,PGⅠ_2的变化及意义

目的探讨实验性大鼠肺血栓栓塞血浆TXA2,PGI2浓度和TXA2,PGI2比值的变化及意义。方法健康Wistar大鼠60只,随机分为栓塞前组,栓塞1h,3h,5h,7h组,每组12只,栓塞组自颈外静脉注入自体血栓混悬液2ml建立肺血栓栓塞模型,栓塞前和注栓后1h,3h,5h,7h各时点收集动脉血,进行动脉血气分析和用放免法检测TXB2,6-Keto-PGF1α及TXA2,PGI2比值。结果组织病理符合肺血栓栓塞的改变;栓塞组注栓后PO2较栓塞前组比较差异显著(P<0.01);血浆TXB23h达高峰值,6-Keto-PGF1α从基线逐渐上升至7h时点达高峰值,二者各时点与栓塞前比较差异有显著性(P<0.01),TXA2,PGI2比值失衡,1h时点达高峰值。结论建立大鼠自体肺栓塞模型成功;缩血管因子TXA2和TXA2,PGI2比值失衡在PTE的初始和早期病理生理过程中发挥重要作用。PGI2对PTE后期病理生理过程有重要影响。     

实验性大鼠肺血栓栓塞血浆TXA2,PGI2的变化及意义

目的探讨实验性大鼠肺血栓栓塞血浆TXA2,PGI2浓度和TXA2,PGI2比值的变化及意义。方法健康Wistar大鼠60只,随机分为栓塞前组,栓塞1h,3h,5h,7h组,每组12只,栓塞组自颈外静脉注入自体血栓混悬液2ml建立肺血栓栓塞模型,栓塞前和注栓后1h,3h,5h,7h各时点收集动脉血,进行动脉血气分析和用放免法检测TXB2,6-Keto～PGF,n及TXA2,PGI2比值。结果组织病理符合肺血栓栓塞的改变;栓塞组注栓后PO2较栓塞前组比较差异显著（P〈0．01）;血浆TX＆3h达高峰值,6-Keto—PGF1a从基线逐渐上升至7h时点达高峰值,二者各时点与栓塞前比较差异有显著性（P〈0．01）,TXA2,PGI2比值失衡,1h时点达高峰值。结论建立大鼠自体肺栓塞模型成功;缩血管因子TXA2和TXA2,PGI2比值失衡在PTE的初始和早期病理生理过程中发挥重要作用。PGI2对PTE后期病理生理过程有重要影响。     

不同溶栓方案治疗肺栓塞时凝血纤溶变化的实验研究

目的观察不同尿激酶溶栓方案治疗肺栓塞后血液凝血及纤溶系统的变化,及其与溶栓效果的关系。方法用99Tcm硫胶体制备放射性栓子,建立犬肺血栓栓塞症(PTE)模型。注栓30min后用不同尿激酶溶栓方案溶栓,观察双肺放射性活度、栓子的溶解速率、凝血酶活性、凝血酶调节蛋白(TM)和D二聚体的变化。实验结束后,取狗肺进行病理分析,观察栓子的分布情况。结果2h溶栓组(UK2h组)溶栓速率为(39.5±13.95)%,12h溶栓组(UK12h组)为(16.9±8.9)%,对照组为(6.2±4.0)%。UK2h组凝血酶活性明显增高,溶栓后3h达到最高点为(0.52±0.22)U/mL,与对照组及UK12h组比较有显著性差异(P<0.01),在UK12h组自溶栓后2h起到12h的凝血酶活性与对照组比较明显升高(P<0.05);溶栓速率与凝血酶活性之间存在明显的正相关关系。UK2h组D二聚体明显升高(P<0.05)。结论2h尿激酶溶栓方案的溶栓速率明显高于12h方案,对临床选择治疗方案有重要指导意义;凝血酶活性可作为观察溶栓疗效的指标之一。     

肺栓塞家兔溶栓前后血浆降钙素基因相关肽水平的变化

目的:探讨兔实验性肺栓塞症(PTE)溶栓前后降钙素基因相关肽(CGRP)的变化及其临床意义.方法:健康中国大耳白兔30只,随机分为肺栓塞组、对照组和溶栓组,每组10只.栓塞组和溶栓组自颈静脉注入自体小血凝块建立家兔急性肺栓塞模型,溶栓组从耳静脉注入尿激酶.分别于术前、术后1 h、2 h、4 h、6 h取血测CGRP,处死后取肺组织HE染色观察.结果:对照组兔肺脏呈正常组织学表现;栓塞组兔的肺脏表面凸凹不平,有散在苍白病灶,并可见点片状出血灶,镜下肺动脉血管内可见有注入的血凝块;溶栓组与栓塞组基本相同,但较轻.栓塞组术后2 h、4 h及溶栓组术后2 h血浆CGRP水平与术前及对照组比较,差异均有统计学意义(P均＜0.01).结论:PTE后CGRP有不同程度升高,溶栓后降低.     

阿司匹林对兔实验性肺血栓栓塞症后血TXA_2、PGI_2变化的影响

目的探讨阿司匹林在肺血栓栓塞(PTE)中的应用价值。方法取健康中国大耳白兔32只,随机分为对照组和实验、、组。对照组经股静脉输入生理盐水,实验组经股静脉输入自体血栓制备急性PTE模型,其中实验、组在自体血栓栓塞前7d分别每天清晨灌服肠溶阿司匹林4mg/kg和8mg/kg,并动态监测栓塞前后血栓素A2(TXA2)的无活性代谢物血栓素B2(TXB2)和前列环素(PGI2)的无活性代谢物6-酮-前列腺素F1α(6-K-PGF1α)的变化。结果对照组各项指标在栓塞前后无显著性差异(P>0.05)。实验、、组的TXB2和6-K-PGF1α在栓塞发生5min即有升高(P<0.05),4h出现下降趋势,其中实验、组在各时点的值低于实验组(P<0.01),实验组低于实验组(P<0.01)。在栓塞后实验、组的TXB2/6-K-PGF1α(T/P)低于实验组(P<0.01),实验组低于实验组(P<0.01)。结论血管活性因子TXA2和PGI2对肺血栓栓塞早期的肺血流动力学变化有重要影响。阿司匹林对改善肺血栓栓塞早期肺血流动力学的紊乱有一定作用。     

前列环素血栓素含量和糖代谢的相关性研究

目的　探讨体外循环(CPB)期间前列环素(PGI2 )、血栓素 (TXA2 )含量及其比值与糖酵解产物血乳酸含量之间的相关关系及可乐定对其的影响。方法　CPB下行择期心脏手术患者 30例,随机分为可乐定组与对照组。两组病人分别于麻醉前、转流前、转流 30min、60min、90min、120min及转流停止后 30min各采集桡动脉血标本测定PGI2、TXA2 含量及血乳酸含量。以PGI2、TXA2 及PGI2 /TXA2 比值为自变量x1、x2 及x3,血乳酸为因变量Y,进行多元直线相关回归分析,并作显著性检验。回归方程为Y=a+b1x1 +b2x2 +b3x3。结果　简单相关系数显示,各变量间的相关系数均有极显著性意义(P<0. 01),两组之间相关系数比较,可乐定组rY. 1、r1. 3的相关性明显高于对照组(P<0. 05),rY. 3、r1. 2相关性极明显高于对照组(P<0. 01)。偏相关系数显示,两组的PGI2含量均与血乳酸含量(rY1. 2)呈极显著性意义负相关(P<0. 01);两组的TXA2 含量均与血乳酸含量〔rY2. 1〕呈极显著性意义正相关(P<0. 01),三个自变量间的偏相关系数显示,PGI2 /TXA2 比值与PGI2〔r31. 2〕呈极显著性意义正相关(P<0. 01)、与TXA2 (r32. 1)呈极显著性意义负相关(P<0. 01),两组比较,可乐定组的rY1.2、rY2. 1相关性极明显高于对照组(P<0. 001)。两组的三元线性回归方程效果检     

重组尿激酶型纤溶酶原激活物治疗大鼠实验性肺血栓栓塞症的探讨

目的观察在不同时间窗重组尿激酶型纤溶酶原激活物(ru-PA)的溶栓效果,并与重组组织型纤溶酶原激活物(rt-PA)的溶栓效果比较。方法通过颈外静脉注入125I标记人纤维蛋白原的大鼠加热血凝块,建立不同时间大鼠的肺血栓栓塞症(PTE)模型。按随机原则将60只大鼠分成三组:①对照组:再分为PTE2h对照组和PTE3d对照组;②PTE2h溶栓组:再分为ru-PA2h组和rt-PA2h组;③PTE3d溶栓组:再分为ru-PA3d组和rt-PA3d组。PTE2h对照组及溶栓组于处理后2h处死大鼠,PTE3d对照组及溶栓组于处理后48h处死大鼠,留取血标本检测血浆纤维蛋白原(FIB)及α2-抗纤溶酶(α2-AP)水平。取血、肺脏及心脏,测量每分钟γ放射性(cpm)。结果(1)rt-PA2h组的溶栓率明显高于ru-PA2h组,ru-PA2h组又明显高于PTE2h对照组(P均=0.000);其血浆FIB、α2-AP水平明显低于ru-PA2h组(P=0.002,P=0.001)及PTE2h对照组(P=0.003,P=0.002),后两组比较差异无统计学意义(P=0.811及0.700)。(2)ru-PA3d组的溶栓率明显高于rt-PA3d组,rt-PA3d组又明显高于PTE3d对照组(P均=0.000);三组间血浆FIB及α2-AP水平比较,差异无统计学意义(P=0.655,P=0.751)。结论(1)ru-PA1mg/kg溶栓对全身纤溶系统无明显影响,而rt-PA1mg/kg溶栓早期影响全身纤溶系统;(2)体内血栓存在的时间影响ru-PA的溶栓效果,ru-PA对新鲜血栓栓塞的即刻溶栓作用不及rt-PA,但对较陈旧血栓栓塞的溶栓效果强于rt-PA。     

实验性大鼠肺血栓栓塞前后血浆TXA2,PGI2和T/P变化及意义

目的:探讨实验性大鼠肺血栓栓塞前后血浆TXA2,PGI2和T/P比值的变化及意义。方法:健康Wistar大鼠60只,随机分为栓塞前组,栓塞1h,3h,5h,7h组,每组12只,栓塞组自颈外静脉注入自体血栓混悬液2ml建立肺血栓栓塞模型,栓塞前和注栓后1h,3h,5h,7h各时点收集动脉血,进行动脉血气分析和用放免法检测TXB2,6-Keto-PGF1α及T/P比值。结果:组织病理符合肺血栓栓塞的改变;栓塞组注栓后PO2较栓塞前组比较差异显著(P<0.01);血浆TXB2 3h达高峰值,6-Keto-PGF1α从基线逐渐上升至7h时点达高峰值,二者各时点与栓塞前比较差异有显著性(P<0.01),T/P比值失衡,1h时点达高峰值。结论:建立大鼠自体肺栓塞模型成功;缩血管因子TXA2和T/P比值失衡在PTE的早期病理生理过程中发挥重要作用。     

肺血栓栓塞症中细胞因子的变化及当归注射液对其的影响

目的 观察内皮素-1(ET-1)、环氧合酶-2(COX-2)在肺内的表达及血浆中血栓烷素B2(TXB2)和6-酮-前列腺素F1α(6-K-PGF1α)的比值(T/P)变化,并探讨当归注射液对其影响.方法 采用自体血栓回输法建立动物模型,将SD大鼠随机分为正常组、肺血栓栓塞症(PTE)模型组和当归治疗组.行常规病理检查,免疫组化法检测肺内ET-1、COX-2蛋白表达水平,放射免疫法测定血浆TXB2、6-K-PGF1α浓度变化.结果 PTE模型组肺组织炎症损伤明显,当归治疗组损伤较轻.ET-1、COX-2蛋白表达水平:PTE模型组较正常组高(P＜0.05);当归治疗组较PTE模型组低(P＜0.05).放免检测T/P:PTE模型组明显较正常组高(P＜0.05);当归治疗后组T/P与正常组间差异无显著性(P＞0.05).结论 当归辅助治疗可明显减少急性肺血栓栓塞症大鼠ET-1、COX-2的表达,调节T/P比例,改善病情.     

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.