腹腔镜胃癌根治术对机体炎性反应和免疫功能的影响

目的:探讨腹腔镜胃癌根治术对机体炎性反应和免疫功能的影响。方法:选择2014年1月-2015年1月于本院接受腹腔镜胃癌根治术患者30例作为腹腔镜组,对照组30例为同期行开腹胃癌根治术患者,比较两组手术前后TNF-α、IL-6水平以及两组手术前后CD4+、CD8+,CD4+/CD8+的变化。结果:两组术前TNF-α、IL-6水平比较差异无统计学意义(P0.05),术后第2天,两组TNF-α、IL-6水平均高于术前,对照组TNF-α、IL-6水平高于腹腔镜组,比较差异均有统计学意义(P0.05);术后第1天,两组CD4+、CD4+/CD8+水平低于术前,比较差异有统计学意义(P0.05),但两组间比较差异无统计学意义(P0.05);两组术后第1天、第7天的CD8+水平比较差异无统计学意义(P0.05)。术后第7天,对照组CD4+、CD4+/CD8+水平低于术前及术后第1天,比较差异有统计学意义(P0.05);但观察组术后第7天CD4+、CD4+/CD8+水平与术前比较,差异无统计学意义(P0.05);观察组术后第7天的CD4+、CD4+/CD8+水平高于对照组,比较差异有统计学意义(P0.05)。结论:腹腔镜胃癌根治术创伤小,对全身炎性反应及免疫功能影响小,较开腹手术能更好地保护患者的免疫功能。     

腹腔镜胃癌根治术围术期患者凝血功能、细胞因子及免疫功能的变化

目的:探究腹腔镜胃癌根治术围术期患者凝血功能、细胞因子及T淋巴细胞的变化及临床意义。方法:选取我院收治的40例腹腔镜胃癌根治术患者和40例开腹胃癌根治术患者,检测并探讨两组围术期凝血功能指标活化部分凝血酶原时间(APTT)、纤维蛋白原(FIB)以及血小板(PLT),细胞因子白介素(IL)-6、C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)及T淋巴细胞(CD4~+、CD8~+以及CD4~+/CD8~+)的变化及临床意义。结果:手术前两组凝血功能相关指标、细胞因子及T淋巴细胞变化不明显(P>0.05);手术后1 d,两组凝血功能、TNF-α、CD4~+以及CD4~+/CD8~+水平显著低于手术前,IL-6、CRP及CD8~+显著高于手术前,且开腹组患者指标变化更明显,差异有统计学意义(P<0.05);手术后3 d,两组APTT、IL-6、CRP、CD4~+、CD8~+以及PLT水平显著低于手术后1d(T1),FIB、TNF-α以及CD4~+/CD8~+水平显著高于T1,开腹组患者凝血功能指标、TNF-α、CD4~+、CD4~+/CD8~+显著低于腹腔镜组,IL-6、CRP、CD8~+显著高于腹腔镜组,差异有统计学意义(P<0.05);手术后5 d,两组APTT、TNF-α、FIB、CD4~+、CD4~+/CD8~+以及PLT水平显著高于手术后3d(T3),IL-6、CRP以及CD8~+水平显著低于T3,开腹组患者凝血功能指标、TNF-α、CD4~+、CD4~+/CD8~+显著低于腹腔镜组,IL-6、CRP、CD8~+显著高于腹腔镜组,差异有统计学意义(P<0.05)。结论:胃癌根治术会引起凝血功能紊乱、免疫功能抑制和炎症反应,随着时间的推移逐渐的回复,与开腹手术相比,腹腔镜胃癌根治术对患者的影响更小,恢复更快。     

腹腔镜与开腹根治手术下胃癌患者的氧化应激、血清炎症因子及感染状况分析

目的 分析腹腔镜与开腹根治手术下胃癌患者的氧化应激、血清炎症因子及感染状况。方法选取我院2017年1月～2019年12月收治的胃癌患者100例,根据手术方式分成两组,腹腔镜组(n=53)应用腹腔镜根治手术治疗,开腹组(n=47)应用开腹根治手术治疗,比较两组患者的氧化应激、血清炎症因子、感染状况。结果 腹腔镜组患者术后1 d、5 d的XOD、MDA水平低于开腹组,而SOD水平高于开腹组,差异均有统计学意义(P0.05)。两组患者术后1 d、术后5 d的XOD、MDA水平高于术前1 d,而SOD水平低于术前1 d,差异均有统计学意义(P0.05)。两组患者术后的IL-6、TNF-α、CRP水平高于术前,差异均有统计学意义(P0.05)。腹腔镜组术后的IL-6、TNF-α、CRP水平低于开腹组,差异均有统计学意义(P0.05)。腹腔镜组并发症发生率为5.67%,开腹组为12.78%,两组患者手术并发症率比较,差异无统计学意义(P0.05)。结论 腹腔镜胃癌根治手术术后患者的氧化应激、血清炎症因子及感染状况较开腹手术更好,说明腹腔镜手术造成的创伤更小,是一种优秀的手术方法。     

腹腔镜胃癌根治术后患者炎症因子指标及凝血功能指标评估

目的观察腹腔镜胃癌根治术对患者术后炎症因子与凝血功能形成的影响。方法选择2016.12～2018.3收治的70例胃癌患者,遵照随机原则分为甲、乙两组,分别给予常规开腹与腹腔镜治疗,比较两组患者术前、术后1 d与3 d时炎症因子与凝血功能。结果术后1 d与3 d,乙组aPTT、Fbg、PLT水平高于甲组(P0.05);与术前相比,术后1 d与3 d时,两组CRP、IL-6、IL-8及TNF-α均高于术前,乙组术后炎症指标更低于甲组(P0.05或P0.01)。结论腹腔镜用于胃癌临床治疗,对机体形成的创伤较小,能降低炎症介质的释放量,减轻炎症反应,其对凝血功能形成的影响更小,有益于患者术后机体功能恢复。     

腹腔镜手术对胃癌患者术后应激反应的影响研究

目的:通过观察腹腔镜与开腹手术对患者术后炎症因子的影响,探讨腹腔镜胃癌手术对患者术后应激反应的影响。方法:选取2012年1月-2014年6月在本院行胃癌手术的患者100例,按照随机数字表法分为开腹手术组和腹腔镜手术组各50例,记录两组的手术指标(手术时间、术中出血量、术后排气时间、住院天数),监测术前及术后的血清胃饥饿素、TNF-α、IL-6、IL-8及CRP水平。结果:(1)两组患者的手术指标比较差异均具有统计学意义(P0.05);(2)术后两组患者的血清胃饥饿素和TNF-α、IL-6、IL-8、CRP水平升高,并于术后24 h达到峰值,开腹手术组明显高于腹腔镜手术组,差异具有统计学意义(t=2.837、2.904、2.671、2.802、6.374,P0.05)。结论:腹腔镜胃癌手术与传统开腹手术相比对患者术后造成应激反应较轻,对患者的创伤较小。     

腹腔镜结直肠癌根治术与开腹结直肠癌根治术对结直肠癌患者术后炎症反应及免疫功能的影响比较

目的比较腹腔镜结直肠癌根治术与开腹结直肠癌根治术对结直肠癌患者术后炎症反应和免疫功能的影响。方法选择2016年1月至2018年3月驻马店市中心医院收治的80例结直肠癌患者为研究对象,按照手术方式分为观察组和对照组,每组40例。观察组患者采取腹腔镜结直肠癌根治术,对照组患者采取传统开腹结直肠癌根治术。记录2组患者的手术时间、术中出血量、切口长度、术后肛门排气时间、淋巴结清扫数目及住院时间;分别于手术前和手术后第2天采用酶联免疫吸附法检测患者血清C反应蛋白(CRP)、白细胞介素-6(IL-6)及肿瘤坏死因子(TNF-α)水平,应用流式细胞仪检测外周血CD4~+、CD8~+、自然杀伤(NK)细胞水平,并计算CD4~+与CD8~+的比值(CD4~+/CD8~+)。结果观察组患者术中出血量少于对照组,切口长度、术后肛门排气时间和住院时间短于对照组(P<0.05); 2组患者手术时间、淋巴结清扫数目比较差异无统计学意义(P>0.05)。2组患者术前血清CPR、IL-6及TNF-α水平比较差异均无统计学意义(P>0.05); 2组患者术后血清CPR、IL-6及TNF-α水平显著高于术前(P<0.05),术后观察组患者血清CPR、IL-6及TNF-α水平显著低于对照组(P<0.05)。2组患者术前外周血CD4~+、CD8~+、CD4~+/CD8~+及NK细胞水平比较差异均无统计学意义(P>0.05)。2组患者术后外周血CD4~+、CD4~+/CD8~+、NK细胞水平显著低于术前,CD8~+水平显著高于术前(P<0.05);术后观察组患者外周血CD4~+、CD4~+/CD8~+、NK细胞水平显著高于对照组,CD8~+水平显著低于对照组(P<0.05)。结论与开腹结肠癌根治术相比,腹腔镜结肠癌根治术具有创伤小、出血量少、机体炎症反应轻、患者术后恢复快等优点,且对患者免疫功能影响小。     

腹腔镜胆囊切除术对患者血清IL-6、IL-10、TNF-α水平的影响

目的探讨腹腔镜胆囊切除术(LC)对胆结石胆囊切除患者白介素-6(IL-6)、白介素-10(IL-10)、肿瘤坏死因子-α(TNF-α)水平的影响。方法选取我院2014年8月-2015年8月收治的60例胆囊结石行胆囊切除术患者,依据手术方式分为观察组和对照组,对照组行开腹胆囊切除术(OC),观察组行LC,观察两组患者手术时间、进食时间、住院时间、肛门排气时间、术中出血量及术前1天、术后第1天、第2天、第3天血清IL-6、IL-10、TNF-α水平。结果观察组患者手术时间、进食时间、住院时间、肛门排气时间明显短于对照组,术中出血量少于对照组(P均<0.05)。手术前两组患者IL-6、IL-10、TNF-α水平差异无统计学意义(P>0.05),手术后第1天IL-6、TNF-α水平即升高,第2天达高峰,第3天开始回落,术后3d的IL-6、TNF-α水平均高于术前(P<0.05);而IL-10术后第1天即降低,第2天最低,第3天开始回升,但均低于术前(P<0.05);术后不同时间点IL-6、TNF-α水平观察组低于对照组(P<0.05),IL-10水平观察组高于对照组(P<0.05)。结论 LC能有效降低胆囊切阿衰术给患者带来的炎症应激反应,优势明显。     

后腹腔镜肾癌根治术治疗T2期肾细胞癌对患者血清CRP、ESR、TNF-α及IL-6影响情况研究

目的探讨T2期肾癌患者采用后腹腔镜根治术治疗的临床效果及对患者术后血清C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)、血沉(ESR)、白细胞介素-6(IL-6)水平的影响。方法选取我院手术治疗的112例T2期肾癌患者(2013年1月至2017年1月)进行回顾性分析,其中56例患者采用后腹腔镜根治术治疗(腹腔镜组)、56例患者采用传统开腹手术(开腹组),对比两种手术方法的围手术期指标、术后血常规及炎性指标。结果腹腔镜组患者的手术时间长于开腹组患者,出血量、术后下床活动时间、术后拔管时间、术后进食时间、住院时间均短于开腹组患者,差异均有统计学意义(P<0.05);术后24h、72h,腹腔镜组患者血清IL-6、TNF-α、CRP、ESR水平均低于同一时间点的开腹组患者,差异有统计学意义(P<0.05);术后24h、72h,腹腔镜组患者WBC水平均低于同一时间点的开腹组患者,Hb、白蛋白高于同一时间点的开腹组患者,差异有统计学意义(P<0.05);腹腔镜组患者的手术并发症率3.57%低于开腹组患者的12.50%,差异有统计学意义(P<0.05)。结论 T2期肾癌患者采用后腹腔镜根治术治疗具有手术创伤小、术后恢复快、患者的炎症反应程度低、并发症更少的优势。     

腹腔镜卵巢囊肿剥除术对卵巢囊肿患者炎症反应和免疫功能的影响

目的探讨腹腔镜卵巢囊肿剥除术对卵巢囊肿患者炎症反应和免疫功能的影响。方法选取2018年1月至2019年3月南召县人民医院收治的90例卵巢囊肿患者,按随机数表法分为开腹组和腹腔镜组,各45例。开腹组接受开腹手术治疗,腹腔镜组接受腹腔镜卵巢囊肿剥除术治疗。比较两组患者手术前后炎性因子水平[肿瘤坏死因子-α(TNF-α)、C反应蛋白(CRP)、白介素-6(IL-6)]和免疫功能指标(CD3~+、CD4~+、CD8~+)。结果术后,两组患者TNF-α、CRP、IL-6水平均高于术前,腹腔镜组患者TNF-α、CRP、IL-6水平均低于开腹组,差异有统计学意义(均P<0.05)。术后,两组患者CD3~+、CD4~+、CD8~+水平均低于术前,腹腔镜组患者CD3~+、CD4~+、CD8~+水平均高于开腹组,差异有统计学意义(均P<0.05)。结论腹腔镜卵巢囊肿剥除术对卵巢囊肿患者术后的免疫功能影响小,还有助于减轻炎症反应。     

腹腔镜手术对胃癌患者血清肿瘤标志物及炎症指标的影响

目的 探讨腹腔镜手术对胃癌患者血清肿瘤标志物及炎症指标的影响.方法 选取2016年1月至2019年12月于本院行手术治疗的100例胃癌患者作为研究对象,随机分为对照组与观察组,每组50例.对照组行开腹远端胃癌根治术,观察组行腹腔镜下胃癌根治术.比较两组血清肿瘤标志物及炎症指标水平.结果 术后1 d,观察组血清糖类抗原125(CA125)、癌胚抗原(CEA)、神经元特异性烯醇化酶(NSE)水平均低于对照组,差异有统计学意义(P<0.05);术后1 d,观察组血清肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6)及C-反应蛋白(CRP)水平均低于对照组,差异有统计学意义(P<0.05).结论 腹腔镜手术治疗胃癌患者疗效显著,可进一步降低肿瘤标志物水平,且炎症反应较轻,值得临床推广应用.     

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.     

APPLICATION OF LORNOXICAM TO PATIENT-CONTROLLED ANALGESIA IN PATIENTS UNDERGOING ABDOMINAL SURGERIES

FOR anesthesiologis s ,treatingpostoperativepainhas alwaysbeen a problem.Althoughopioidshave been provedtobe effective,theirsideeffectscouldnotbeignored.With thedevelopmentofscienceand pharmacology,many drugs with aspectsof satisfactoryanalgesicefficacyand couldbe welltoleratedby patientshave been developed.And lornoxicamisone of them, which isa non-steroidalanti-inflammatorydrug (NSAID ), with analgesic, anti-infl-ammatory,andantipyreticproperties.Itseliminationhalf-time(3 to 5 hours) isle…     

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.     

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.