高血压病人红细胞变形能力与红细胞ATP酶活性及细胞内离子水平关系的研究

通过观察６６例高血压病（ＥＨ）病人红细胞变形能力（ＥＤ）和红细胞ＡＴＰ酶活性，细胞内离子浓度变化及其相互关系。结果显示，ＥＨ病人红细胞滤过指数（ＩＦ）较对照组明显增高（Ｐ＜０．００１），红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶和Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶活性、细胞内Ｋ＋，Ｍｇ２＋－浓度明显降低（Ｐ＜０．００１），而细胞内Ｎａ＋，Ｃａ２＋浓度明显增高（Ｐ＜０．００１），且随着ＥＨ病程进展而逐渐明显（Ｐ＜０．００１）。ＥＨ病人红细胞ＩＦ与红细胞Ｎａ＋－Ｋ＋－ＡＴＰ酶、Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶活性及Ｋ＋，Ｍｇ２＋浓度呈明显负相关（Ｐ＜０．００１），与Ｃａ２＋，Ｎａ＋浓度呈正相关（Ｐ＜０．００１）。结果提示ＥＨ病ＨＥＤ降低与红细胞膜ＡＴＰ酶活性降低及离子浓度异常有关。     

妊高征患者红细胞钙、镁和环核苷酸含量变化

目的 探讨妊高征患者红细胞内外的Ｃa^2 、Ｍg^2 和环磷酸腺苷（cＡＭＰ）、环磷酸鸟苷（cＧＭＰ）的含量变化，相互关系及与妊高征发病机制的关系。方法 采用生化方法测定２５例妊高征患者和２７例政党晚期妊娠妇女红细胞膜ＡＴＰ酶活性１红细胞内外Ｃa^2 、Ｍg^2 含量；采用竞争性蛋白质结合分析方法测定血浆cＡＭＰ、放射免疫方法测定cＧＭＰ。结果 妊高征组红细胞膜Ｎa^ -、K^ -ATP酶和Ｃa^2 －ＡＴＰ酶活性明显降低（Ｐ＜０.００１），而Ｍg^2 －ＡＴＰ活性未见改变。红细胞内Ｃa^2 含量显著增高（Ｐ＜０.０１）。血浆Ｃa^2 、Ｍg^2 的浓度显著低于对照组（Ｐ＜０.０５），而血浆cAMP和cＧＭＰ的浓度显著增高（Ｐ＜０.０５）。妊高征组的平均动脉压（ＭＡＰ）与红细胞膜的Ｃa^2 -、Na^ -、K^ -ATPase的活性呈负相关，与Ｃa^2 、cＡＭＰ和cＧＭＰ呈正相关。Ｃa^2 －ＡＴＰ酶与Ｃa^2 呈负相关；Ｃa^2 与cＡＭＰ和cＧＭＰ呈正相关。结论 在妊高征的发生机制中缺镁比缺钙更有意义。细胞Ｃa^2 转运障碍和cＡＭＰ、cＧＭＰ的代谢异常可能与妊高征的发生有关，它们在妊高征的发展和转归中起着举足轻重的作用。     

风心瓣膜病变患者红细胞膜钠、钙泵活性和脂质过氧化的变化

用酶解法和Ｈ２Ｏ２分解法分别测定２８例风心瓣膜病变患者红细胞膜钠泵（Ｎａ＋、Ｋ＋－ＡＴＰ酶）、钙泵（Ｃａ２＋、Ｍｇ２＋－ＡＴＰ酶）活性和膜过氧化氢酶（ＣＡＴ）活性，并用硫代巴比妥酸比色法测定患者红细胞膜脂质过氧化物（ＬＰＯ）含量。患者红细胞膜Ｎａ＋、Ｋ＋－ＡＴＰ酶活性和Ｃａ２＋、Ｍｇ２＋－ＡＴＰ酶活性分别显著低于正常人３４．７５％（Ｐ＜０．０１）和２６．７７％（Ｐ＜０．０１）；ＣＡＴ活性显著低于正常人２０．０７％（Ｐ＜０．０１）；而患者ＬＰＯ含量却显著高于正常人９７．５０％（Ｐ＜０．０１）。结果提示风心病患者瓣膜病变与质膜钠、钙泵活性变化以及膜脂质过氧化作用有关。     

体外循环脂质过氧化对红细胞钙的影响

①目的研究体外循环中脂质过氧化对红细胞钙的影响。②方法对行体外循环的病儿分别于转流前、转流３ｍｉｎ，转流结束、转流后２ｈ，２４ｈ采抗凝血。测定血浆及红细胞膜过氧化脂质、红细胞钙、红细胞膜Ｃａ２＋，Ｍｇ２＋－ＡＴＰ酶和Ｎａ＋，Ｋ＋－ＡＴＰ酶活性。③结果转流３ｍｉｎ时血浆和红细胞膜过氧化脂质即增高，转流结束达到高峰（ｔ＝３．５２７，２．９２１，Ｐ均＜０．０１）；转流开始红细胞钙即升高（ｔ＝２．９３７，Ｐ＜０．０１），转流结束后２ｈ达到高峰（ｔ＝３．４２６，Ｐ＜０．０１）；红细胞膜Ｃａ２＋，Ｍｇ２＋－ＡＴＰ酶和Ｎａ＋，Ｋ＋－ＡＴＰ酶活性转流３ｍｉｎ时暂时性升高后迅速降低，转流结束后２ｈ达最低点（ｔ＝２．８１６，２．８５２，Ｐ均＜０．０１）。转流结束后２４ｈ除红细胞钙仍高于转流前（ｔ＝２．０２８，Ｐ＜０．０５）外，其它各值均恢复正常。④结论氧自由基介导的脂质过氧化损伤是体外循环中红细胞钙超负荷的重要原因之一。     

尿毒症病人红细胞变形能力和形态的变化

①目的探讨尿毒症病人红细胞变形能力（ＥＤ）和形态变化与红细胞膜脂质组成和ＡＴＰ酶活性的关系。②方法检测了４０例尿毒症病人和３８例健康人ＥＤ和红细胞形态变化，同时观察了红细胞膜胆固醇（Ｃｈ）、磷脂（ＰＬ）、脂质过氧化物（ＬＰＯ）和Ｎａ＋－Ｋ＋－ＡＴＰ酶、Ｃａ２＋－ＡＴＰ酶及Ｍｇ２＋－ＡＴＰ酶活性的变化。③结果尿毒症病人红细胞滤过指数（ＦＩ）和红细胞形态异常率明显增高，与对照组比较差异有极显著性（ｔ＝４．５２６，３．９８５，Ｐ＜０．００１）。异常形态红细胞有痘痕红细胞、口形红细胞、球形红细胞、嵴形红细胞和棘形红细胞，其异常率均明显高于对照组（ｔ＝３．５１１～４．２６９，Ｐ＜０．００１）。尿毒症病人红细胞Ｎａ＋－Ｋ＋－ＡＴＰ酶和Ｃａ２＋－ＡＴＰ酶活性、ＰＬ明显降低，而Ｃｈ／ＰＬ和ＬＰＯ明显增高，与对照组比较差异有极显著性（ｔ＝３．６２０～４．７１５，Ｐ＜０．００１）。尿毒症病人红细胞ＦＩ，红细胞异常率与膜Ｎａ＋－Ｋ＋－ＡＴＰ酶、Ｃａ２＋－ＡＴＰ酶活性和ＰＬ呈负相关（ｒ＝－０．４４９～－０．５７４，Ｐ＜０．００１）；而与Ｃｈ／ＰＬ，ＬＰＯ呈正相关（ｒ＝０．４６６～０．６２０，Ｐ＜０．００１）。④结论尿毒症病人的     

非胰岛素依赖型糖尿病病人红细胞镁浓度变化及镁对红细胞变形能力的影响

检测了６４例非胰岛素依赖型糖尿病（ＮＩＤＤＭ）病人红细胞镁（Ｅ－Ｍｇ（２＋））浓度变化，同时观察了镁在体外对ＮＩＤＤＭ病人红细胞变形能力（ＥＤ）、红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶活性、Ｅ－Ｍｇ（２＋）和红细胞钙（Ｅ－Ｃａ（２＋））浓度的影响。结果显示，ＮＩＤＤＭ病ＨＥ－Ｍｇ（２＋）浓度较对照组明显降低（Ｐ＜０．００１），有血管病变者降低更明显。ＮＩＤＤＭ病人红细胞与镁共同孵育后，红细胞滤过指数（ＩＦ）、Ｅ－Ｃａ（２＋）明显降低，Ｅ－Ｍｇ（２＋）和红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶活性明显增高，与孵育前比较差异有极显著性（Ｐ＜０．００１），与对照组比较差异无显著性（Ｐ＞０．０５）。提示镁对改善ＮＩＤＤＭ病人血液流变学、减少血管病变的发生有重要意义。     

脑梗塞病人红细胞变形能力变化及其机制探讨

①目的探讨脑梗塞病人红细胞变形能力（ＥＤ）变化的机制。②方法检测了３２例脑梗塞病人和３５例健康查体者ＥＤ，同时测定了红细胞内钙、镁浓度及红细胞膜Ｎａ＋，Ｋ＋－ＡＴＰａｓｅ，Ｃａ２＋－ＡＴＰａｓｅ和Ｍｇ２＋－ＡＴＰａｓｅ活性。③结果脑梗塞病人红细胞滤过指数（ＦＩ）和红细胞内Ｃａ２＋浓度明显高于对照组（ｔ＝８．０７，１６．０８，Ｐ＜０．０１），红细胞膜Ｎａ＋，Ｋ＋－ＡＴＰａｓｅ和Ｃａ２＋－ＡＴＰａｓｅ活性明显低于对照组（ｔ＝４．０４，１１．９２，Ｐ＜０．０１），红细胞内Ｍｇ２＋浓度及红细胞膜Ｍｇ２＋－ＡＴＰａｓｅ活性与对照组相比无显著差异（ｔ＝０．３８，１．８３，Ｐ＞０．０５）。④结论红细胞内Ｃａ２＋浓度增高及红细胞膜Ｃａ２＋－ＡＴＰａｓｅ活性降低可能是导致脑梗塞病人ＥＤ降低的主要因素之一     

高血糖对非胰岛素依赖型糖尿病患者红细胞（Ca~（2＋）－Mg~（2＋））－ATP酶的影响

为了解高血糖对非胰岛素依赖型糖尿病（ＮＩＤＤＭ）患者红细胞膜（Ｃａ２＋－Ｍｇ２＋）－Ａｒｐ酶的影响，采用改良的Ｈａｎａｈａｎ和Ｌｕｔｈｒａ法测定了红细胞膜（Ｃａ２＋－Ｍｇ２＋）－ＡＴＰ酶活性。结果表明，ＮＩＤＤＭ患者红细胞膜（Ｃａ２＋－Ｍｇ２＋）－ＡＴＰ酶活性降低，且与空腹血糖、糖化血红蛋白、果糖胺及红细胞变形指数呈负相关，后者与红细胞内Ｃａ２＋浓度呈正相关。说明（Ｃａ２＋－Ｍｇ２＋）－ＡＴＰ酶活性下降时，红细胞变形能力降低，可能与患者红细胞膜蛋白的过度糖化及细胞内Ｃａ２＋浓度的增高有关。     

老年高血压病人红细胞变形能力与膜钙依赖中性蛋白酶活性的关系

①目的探讨老年高血压病人红细胞变形能力（ＥＤ）与红细胞膜钙依赖中性蛋白酶（Ｃａｌｐａｉｎ）活性的关系。②方法采用红细胞变形能力测定仪、分光光度计和凝胶电泳法分别检测了６８例老年高血压病人和６０例老年前期高血压病人及８０例健康人红细胞滤过指数（ＥＦＩ）、红细胞膜Ｃａｌｐａｉｎ和Ｃａ２＋－ＡＴＰ酶活性及红细胞膜收缩蛋白（ＳＰ）相对含量的变化。③结果老年高血压病人ＥＦＩ，Ｃａｌｐａｉｎ活性明显增高，Ｃａ２＋－ＡＴＰ酶活性和ＳＰ相对含量明显降低，与老年前期病人和健康对照组比较差异均有极显著性（ｔ＝３．１７７～５．２０９，Ｐ均＜０．００１）。老年前期高血压病人各指标变化较老年前期健康人亦明显（ｔ＝２．６２６～３．０８４，Ｐ均＜０．０１）。老年高血压病人ＥＦＩ与Ｃａｌｐａｉｎ活性呈正相关（ｒ＝０．６２１，Ｐ＜０．００１），与Ｃａ２＋－ＡＴＰ酶活性和ＳＰ相对含量呈负相关（ｒ＝－０．５７６，－０．４９６，Ｐ＜０．００１）；红细胞膜Ｃａ２＋－ＡＴＰ酶活性和ＳＰ含量与Ｃａｌｐａｉｎ活性呈负相关（ｒ＝－０．５１１，－０．５２９，Ｐ＜０．００１）。④结论老年高血压病人ＥＤ降低与红细胞膜Ｃａｌｐａｉｎ活性增高所致的膜蛋白溶解和破坏有     

高血糖对非胰岛素依赖型糖尿病患者红细胞（Ca^2＋—Mg^2＋）…

为了解高血糖对非胰岛素依赖型糖尿病（ＮＩＤＤＭ）患者红细胞膜（Ｃａ＾２＋－Ｍｇ＾２＋）－Ａｒｐ酶的影响。采用改良的Ｈａｎａｈａｍ和Ｌｕｔｈｒａ法测定了红细胞膜（Ｃａ＾２＋－Ｍｇ＾２＋）－ＡＴＰ酶活性。结果表明，ＮＩＤＤＭ患者红细胞膜（Ｃａ＾２＋－Ｍｇ＾２＋）－ＡＴＰ酶活性降低，且与空腹血糖、糖化血红蛋白、果糖胺及红细胞变形指数呈负相关，后者与红细胞内Ｃａ＾２＋浓度呈正相关，说明（Ｃａ＾２＋－Ｍｇ＾     

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.     

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.     

Scientific principles and rigorous processes should be followed in developing clinical guidelines for therapeutic interventions of integrative medicine

A clinical guideline for the therapeutic interventions of integrative medicine may be defined as a written document which states a series of recommendations on therapeutic interventions of integrative medicine for a special disease or condition. The guideline may provide assistance to medical professionals in making clinical decisions aimed at improving the clinical outcome of patients and reducing the costs of medical care（~＇4~. Recommendations issued by a guideline should be based on the best available evidence in both Western and Chinese medicine. For fulfilling this purpose, the development of clinical guidelines for therapeutic interventions in the field of integrative medicine should follow scientific principles and undergo a rigorous processes.