CAPD并发慢性腹膜炎对营养状态的影响及护理研究

目的：探讨持续不卧床腹膜透析（CAPD）并发慢性腹膜炎对营养状态的影响,为预防腹膜炎、改善患者的营养状态提出科学的护理干预依据;方法：选择CAPD患者50例,平均分2组：观察组和对照组。观察组为CAPD并发慢性腹膜炎多次急性发作患者,对照组为CAPD未并发过腹膜炎患者。观察营养指标：血清白蛋白（ALB）、前白蛋白（PA）、和转铁蛋白（TRF）、测定血清总蛋白（TP）,瘦体重,瘦体重%和标准化总氮出现率相当蛋白nPNA（g/（kg.d）。检测生化指标、微炎症指标[超敏C反应蛋白（hs-CRP）、肿瘤坏死因子-α（TNF-α）、白细胞介素-6（IL-6）]、24小时腹透液中丢失的蛋白量,运用多元Logistic回归分析,进行主观性营养评估（SGA）。结果：观察组营养状态指标中,ALB（mmol、HB（mmol）、PA（mmol）、TF （mmol）、LBM（%）、nPNA（g/（kg. d）,低于对照组,P〈0.1,有统计学意义,炎症因子TNF-a （pg/ml）和IL-6水平明显高于对照组（P〈0.05）。结论：CAPD并发慢性腹膜炎会导致和加重患者营养不良,据临床观察腹膜炎患病次数越多,病程越长,病情越重,患者营养状态越差,反之营养不良会加重腹膜炎的发生。有研究报道：根据MIS（营养不良-炎症评分）,每增加1分则患腹膜炎的相对风险为1.185（1.036~1.355P〈0.05）[1],因此对CAPD患者必须提出科学合理护理干预,预防腹膜炎的发生,从而改善患者的营养状态,延长患者生命,提高患者生存率。     

腹膜透析患者微炎症状态对营养状况的影响

目的探讨腹膜透析（腹透）患者体内的微炎症因子水平及其对营养状况的影响。方法采用酶联免疫吸附试验（ELISA）检测45例腹透患者和20名健康人血清中微炎症因子超敏C反应蛋白（hs-CRP）、IL-6、TNF-α的表达水平,并对两组作统计分析。按hs-CRP≤3mg/L和hs-CRP〉3mg/L将45例腹透患者分为两组,比较两组间营养指标血清白蛋白（ALB）、前白蛋白（PA）、转铁蛋白（TF）和主观营养评估法（SGA）的变化及其与炎症因子的关系。结果腹透组患者血清hs-CRP、IL-6、TNF-α水平均显著高于健康对照组;hs-CRP升高组患者ALB、PA、TF和SGA水平均显著低于hs-CRP正常组,以上差异均有高度统计学意义（均P〈0.01）。结论腹透患者存在微炎症状态,微炎症状态影响营养不良的发生。     

持续非卧床腹膜透析患者营养综合评估及相关分析

目的：调查持续非卧床腹膜透析(continuous ambulatory peritoneal dialysis,CAPD)患者综合营养情况,并进行相关影响因素分析。方法： 56例 CAPD患者按透析龄分为透析龄 ＜36 个月组和透析龄≥36 个月两组,比较各营养代谢指标的差异,并进行相关分析。行半定量主观综合营养评分（subjective global assessment,SGA）;生化指标包括：血清白蛋白(AlB)、前白蛋白(Pre-A)、转铁蛋白（Tf）、血红蛋白( Hb) 、胆固醇(TC)、甘油三酯(TG)、C反应蛋白(CRP)、血肌酐、血尿素氮、24 h腹透液和尿液中的尿素氮和肌酐等,计算尿素清除指数（Kt/V）、残余肾功能（residual renal function,RRF）。结果: 长透析龄组的SGA评分高于短透析龄组、血清营养指标低于短透析龄组(P<0.05),RRF、Kt/V低于短透析龄组(P<0.05),CRP高于短透析龄组(P<0.05)。透析时间与白蛋白、前白蛋白、转铁蛋白、血红蛋白、Kt/V、RRF呈负相关,与CRP、SGA评分呈正相关。结论: 随着透析龄的延长,残余肾功能逐步衰退,透析充分性降低,助长炎症反应,加重营养不良。     

尿毒症腹膜透析患者同型半胱氨酸清除机制的临床研究

目的:探讨持续不卧床腹膜透析(CAPD)及残余肾功能(RRF)对尿毒症患者血同型半胱氨酸(Hcy)的清除的影响.方法:留取22例CAPD患者24 h的透出液及尿液,同日取血标本,用高压液相色谱技术(HPLC)测定血清、透出液的总同型半胱氨酸(tHcy)浓度;常规检测血、透出液和尿液的尿素氮、肌酐值;计算总尿素清除指数(Kt/V)、RRF、腹膜tHcy清除率和每日腹透液tHcy清除量.结果:CAPD患者的血tHcy平均浓度高于正常人[(15.95±3.77) vs (8.87±2.43) μmol/L,P＜0.05],平均每日tHcy清除量为(15.24±4.52) μmol.RRF与血tHcy浓度无关,与每日腹透液tHcy清除量呈负相关;Kt/V与每日腹透液tHcy清除量呈正相关,与血tHcy浓度无关.结论:CAPD患者血tHcy水平较正常人升高;RRF及Kt/V对CAPD患者血tHcy浓度的降低影响较小.     

腹膜透析患者腹膜转运类型与营养状况的相关性研究

目的探讨持续性非卧床腹膜透析(CAPD)患者腹膜转运类型对其营养状况的影响。方法选择2010年1月至2012年12月在该院腹膜透析中心行CAPD的89例患者,根据腹膜平衡试验腹膜透析液与血中肌酐比值(D/Pcr)将患者分为LA组(低平均转运)和HA组(高平均转运),比较2组患者的营养状况,包括血清清蛋白(ALB)、前清蛋白(PA)、血清转铁蛋白(TF)、血红蛋白(Hb)、主观综合性营养评分(SCA)、瘦体质量(LBM)和标准化总氮出现率相当蛋白(nPNA),并对D/Pcr与营养指标进行相关性分析。结果 HA组D/Pcr显著高于LA组(P<0.01);HA组患者ALB、PA、TF、Hb和SGA均显著低于LA组患者(P<0.01),但两组患者的nPNA差异无统计学意义(P>0.05);CAPD患者D/Pcr与ALB、TF、Hb和SGA呈显著负相关(P<0.01),但是与PA、LBM和nPNA不相关(P>0.05)。结论腹膜透析患者营养状态与腹膜转运类型相关,高平均转运腹膜透析患者营养状态较低平均转运者差,故应加强对该类患者的营养指导。     

腹膜透析患者营养不良和蛋白质能量摄入不足的临床影响因素分析

目的　研究腹透患者营养不良和蛋白质能量摄入不足的发病情况和临床影响因素。方法　对北京 4个腹透中心共 90例持续不卧床腹膜透析 (CAPD)患者进行营养状况评价 ,包括主观综合性营养评估 (SGA) ,食谱调查 ,直接人体测量 ,生化参数的测定等 ,并调查社会功能及焦虑抑郁状况。以SGA为营养不良的判断标准 ,将患者分为营养良好、轻中度营养不良和重度营养不良 3组。用多元回归方法分析营养不良和蛋白质能量摄入不足的影响因素。结果　营养不良发生率为4 7 8% ,其中重度营养不良为 13.3%。营养程度不同的 3组间以下指标比较 :平均每日每公斤体重能量和蛋白质摄入 (DEI、DPI)、上臂围 (AC)、三头肌皮褶厚度 (TSF)、上臂肌围 (AMC)、血白蛋白 (Alb)、前白蛋白 (PA)、转铁蛋白 (TF)、氮出现率相当蛋白 (nPNA)、瘦体重 (LBM)和瘦体重百分比 (LBM % )差异均有显著性意义 (P <0 .0 0 1～ 0 .0 5 )。营养状况的正相关因素是DPI(P <0 .0 5 )、DEI(P <0 .0 5 )、标准化TCcr(P <0 .0 1)、GFR(P =0 .0 6 9) ,负相关因素为透析时间 (P =0 .12 ) ,糖尿病 (P <0 .0 5 )。本组患者DPI为 (0 .74± 0 .2 6 )g·kg-1·d-1,DEI为 (113± 2 9)kJ·kg-1·d-1。DEI的负相关因素是焦虑积分 (P<0 0 1)和不坚持体力活动 (P <0 .0 5 )     

糖尿病与非糖尿病CAPD患者腹透液蛋白丢失及营养状况比较

目的比较糖尿病与非糖尿病持续不卧床腹膜透析（CAPD）患者的每日腹透液蛋白丢失量及营养状况,提出减少糖尿病CAPD患者腹透液蛋白丢失对于改善营养状况的重要意义。方法选择40例CAPD患者,其中糖尿病组17例,非糖尿病组23例,收集其在透析半年时的24h透出液蛋白量、血清白蛋白（ALB）水平及SGA评分数据、腹膜平衡试验（PET）检查4h血肌酐/腹透液肌酐（D/P）。结果 （1）糖尿病组透出液蛋白显著高于非糖尿病组[（5.72±2.25）（3.55±1.01）g,〈0.01]）,（2）糖尿病组血清ALB水平显著低于非糖尿病组[（34.9±2.02）（37.2±1.90）g/L,〈0.05]）（,3）根据SGA评分,糖尿病CAPD患者的营养不良发生率明显高于非糖尿病CAPD患者（41.2%8.7%,〈0.05）（,4）糖尿病CAPD患者透出液蛋白丢失量与血清ALB水平之间（=-0.2422,〈0.01）呈显著负相关关系。（5）PET检查4h肌酐D/P,糖尿病组（0.57±0.10）,非糖尿病组（0.55±0.07）,两组数据比较差异无统计学意义[（0.57±0.10）（0.55±0.07）,〉0.05]。结论糖尿病CAPD患者透出液蛋白丢失量相对较多,是引起营养不良发生的一个重要因素,减少透出液中蛋白的丢失能减少该类患者营养不良的发生率。     

持续性不卧床腹膜透析患者并发低蛋白血症临床分析

目的：研究腹膜透析患者并发低蛋白血症的发生情况,探讨其与C反应蛋白（C-reac-tive protein,CRP）及其与各种炎性并发症的关系。方法：横断面调查：对2006年1月至2009年6月入院的60例持续性不卧床腹膜透析（CAPD）患者进行血清白蛋白（ALB）水平及其引发的相关并发症进行调查。根据ALB水平分为A组和B组,其中A组为营养良好,ALB正常;B组合并低白蛋白血症。比较两组间炎症因子CRP、转铁蛋白（TF）和主观营养评估法（SGA）的变化及其与临床并发症的关系。采用t检验及Pearson相关分析。结果：60例CAPD患者中,B组腹膜透析患者的患者CRP水平（8.4±1.32）mg/L显著高于A组（2.14±0.87）mg/L（P〈0.01）;腹膜炎发生率为6.7%,肺炎发生率为13.3%;心血管疾病的发生率为16.7%,均明显高于A组。结论：CAPD患者营养不良低白蛋白血症,并发炎症及心血管疾病的发生率皆高于营养良好者。应重视腹膜透析患者营养不良-炎症-心血管疾病（动脉粥样硬化）综合征（M IA综合征）的诊治。     

腹透患者透析效能及营养状况的评价

目的 :探讨腹透患者营养状况、透析充分性的影响因素以及残余肾功能对二者的影响。方法 :采用主观综合营养评价 (SGA)并测血浆白蛋白 (AL b)、前白蛋白 (PA)、转铁蛋白 (TF)、氮表现的蛋白质水平 (n PNA)、3日膳食摄入记录法分析每日能量摄入营养指标 ,计算尿素清除指数 KT/ V (Urea)、肌酐清除率 (Ccr)和残肾功能 (RRF)。结果 :2 2例腹透患者中营养良好 9例 ,占 40 .9% ,轻～中度营养不良 1 2例 ,占 5 4.5 % ,重度营养不良 1例 ,占 4.5 %。腹透龄越大 ,透析充分性越差。营养良好与营养不良两组患者在 RRF、PA、Alb、TF无差异性…     

慢性肾功能衰竭时瘦素水平与营养不良关系的研究

目的　了解慢性肾功能衰竭 (CRF)时血清瘦素浓度及高瘦素血症与CRF营养不良的关系。方法　CRF组 112例 ,分为非透析亚组 74例、血液透析 (血透 )亚组 2 9例和腹膜透析 (腹透 )亚组 9例 ;正常对照组 13例。采用ELISA法测定血清瘦素水平 ,同时测定前白蛋白、白蛋白、转铁蛋白和血脂 ;采用双能量X线吸收法(DEXA)测定受试者体脂含量 ;采用主观全面营养评价法 (SGA)评估受试者营养状况。结果　CRF组血清瘦素浓度为 (8.4 9± 0 .97) μg/L ,显著高于正常对照组的 (7.6 3± 0 .16 ) μg/L(取自然对数值 ,P <0 .0 1) ,其中以腹透亚组血清瘦素水平 (9.30± 0 .79) μg/L升高最为明显。CRF组前白蛋白、白蛋白、转铁蛋白等营养客观生化指标均显著低下。在血透亚组 ,血清瘦素水平与白蛋白呈显著负相关 (r =- 0 .195 ,P <0 .0 5 )。SGA评估显示CRF组存在营养不良 ,且营养状况越差 ,血清瘦素水平越高 (P <0 .0 1)。CRF组体脂含量与对照组相比 ,差异无显著性 ;血透、腹透及非透析亚组体脂百分比均与瘦素水平呈正相关 (P <0 .0 5 ) ,腹透亚组相关性最强。结论　CRF时存在高瘦素血症 ,且可能参与营养不良的发病     

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.