低剂量低分子肝素对内毒素诱发的急性肺损伤的影响

目的 探讨低剂量低分子肝素(LMWH)对内毒素(LPS)诱发的急性肺损伤(ALI)的影响.方法 选取36只雄性SD大鼠分为3组:正常对照组(A组),LPS组(B组)和LPS+ LMWH组(C组),每组12只.B、C组腹腔注射6 mg/kg LPS诱发ALI.C组腹腔注射低分子肝素100 U/kg,B组腹腔注入同等容积的生理盐水.6h后处死动物,光镜下观察各组大鼠肺组织病理改变,行动脉血气分析、检测肺湿质量/干质量(W/D)比值和支气管肺泡灌洗液(BALF)中总蛋白浓度;测定肺组织髓过氧化物酶(MPO)活性、丙二醛(MDA)水平;ELISA法测定血浆中肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)及白细胞介素6(IL-6)水平.结果 B、C组PaO2、pH值低于A组,C组与B组相比明显升高(P＜0.05).B、C组大鼠肺W/D、BALF总蛋白及肺组织MDA、MPO水平明显高于A组(P＜0.01);C组与B组相比,肺W/D、BALF中蛋白及肺组织MDA、MPO水平明显下降(P＜0.05).B、C组大鼠血浆中TNF-α、IL-1β及IL-6水平较A组明显升高(P＜0.01),而C组较B组明显降低(P＜0.01).结论 LMWH处理能够减轻LPS诱发的急性肺损伤.     

姜黄素对脂多糖诱导大鼠急性肺损伤的保护作用

目的观察姜黄素对脂多糖诱导大鼠急性肺损伤（ALI）的保护作用。方法 Wistar大鼠随机分为6组：空白组、模型组、地塞米松组和姜黄素三个不同剂量组（50、100、200mg.kg-1）。LPS气管滴注复制ALI模型,6h后收集支气管肺泡灌洗液（BALF）,检测TNF-α、IL-1β浓度及蛋白含量;称重法检测肺组织湿/干重比和肺含水量。结果姜黄素剂量依赖性降低LPS所致ALI模型BALF中TNF-α、IL-1β及蛋白量增加,降低肺湿/干重比、肺含水量。结论姜黄素对LPS所致ALI有保护作用,其可能的机制为调节炎症介质的产生有关。     

异丙酚对内毒素诱导的急性肺损伤的保护作用

目的：探讨不同剂量异丙酚对内毒素(LPS)诱导的大鼠急性肺损伤(ALI)的保护作用。方法：股静脉注射内毒素(LPS，5mg／kg)建立大鼠ALI模型。24只雄性Wistar大鼠随机分为4组：空白对照组(C组)；LPS对照组(L组)；低剂量异丙酚治疗组(Lp1组)；高剂量异丙酚治疗组(Lp2组)，每组6只。按预设时相采集标本，酶联免疫吸附法(ELISA)测定血清和支气管肺泡灌洗液(BALF)中肿瘤坏死因子-α(TNF-α)、白细胞介素-β(IL-1β)、白细胞介素-10(IL-10)水平；以肺湿／干重比反应肺含水量；并观察BALF中性粒细胞计数比、蛋白含量。结果：内毒素组大鼠肺湿／干重比、BALF中性粒细胞计数比及蛋白含量均明显增加，血清及BALF中TNF-α、IL-1β、IL-10水平显著升高，而异丙酚治疗组的各项指标均较内毒素组减轻，大剂量作用更明显。结论：异丙酚对内毒素诱导的大鼠急性肺损伤有保护作用，大剂量作用较明显。     

地塞米松对脂多糖致大鼠急性肺损伤的治疗作用

目的:探讨急性肺损伤(Acate lung injury,ALI)发生早期给予地塞米松的治疗作用.方法:大鼠尾静脉注射5mg/kg脂多糖(Lipopolysacharide,LPS),造成ALI模型.于注射LPS 1 h后,腹腔注射地塞米松(10 mg/kg),1 h后采集标本,分别测定血清蛋白含量、肺泡灌洗液(Broncho alveolar lavage fluid,BALF)中蛋白、TNF-α、IL-8、ICAM-1的含量,计算肺通透指数(Lung alveolar permeability index,LPI)、肺湿/干重比,检查肺组织病理学变化情况.实验平行设置生理盐水对照组和LPS损伤组.结果:肺组织病理切片检查表明,LPS组肺间质水肿、出血,大量炎性细胞浸润,而地塞米松组肺组织损伤显著轻于LPS组.地塞米松组肺湿/干重比、BALF中PMN比、LPI均显著低于LPS组(P<0.05),与正常对照组相比没有显著差异.LPS组BALF中TNF-α、IL-8、ICAM-1浓度高于正常对照组(P<0.05),而地塞米松组与对照组相比,差异无统计学意义(P>0.05 ).结论:在ALI发生早期给予大剂量地塞米松,可以减轻肺组织损伤,减少肺组织液渗出和中性粒细胞聚集.     

ω-3脂肪酸对于大鼠呼吸机相关性肺损伤的预防作用及机制研究

目的 研究ω-3脂肪酸对呼吸机相关性肺损伤(VILI)大鼠炎性反应的影响,探讨ω-3脂肪酸对于VILI的预防作用及其机制.方法 48只SD大鼠按随机数字表法分成对照组(C组),VILI模型组(M组),ω-3脂肪酸干预1、2、3、4组(I1组、I2组、I3组、I4组,制模前0.5h分别静脉注射ω-3脂肪酸60、120、180、240mg/kg).除C组外各组均行机械通气,3h后处死大鼠.取肺组织测定肺湿/干重(W/D)比值、肺组织髓过氧化物酶(MPO)水平;收集支气管肺泡灌洗液(BALF)测定总蛋白水平;取血测定白细胞介素-10(IL-10)、肿瘤坏死因子-α(TNF-α)水平.结果 与M组比较,随着ω-3脂肪酸用量增加,I1、I2、I3、I4组肺W/D比值下降(P＜0.01);BALF中总蛋白水平、MPO水平、血TNF-α水平逐渐降低(P＜0.01);血IL-10水平升高(P＜0.05).结论 ω-3脂肪酸可通过抗炎、抗氧化应激、减少渗出等机制发挥对肺的保护作用,还可减轻VILI,其最适剂量范围为120～180mg/kg.     

NMDA受体阻断剂美金刚胺对小鼠内毒素急性肺损伤的保护作用

目的:探讨NMDA受体阻断剂美金刚胺对脂多糖(LPS)诱导的小鼠急性肺损伤(ALI)的保护作用.方法:健康成年雄性昆明小鼠随机分为正常组、美金刚胺组、ALI组和美金刚胺+ALI组.腹腔注射美金刚胺(10 mg/kg) 30 min后腹腔注射LPS(10 mg/kg)制作ALI小鼠模型.各组小鼠处理后6h测定全肺测定湿/干重比值;采用苏木精-伊红染色观察肺组织病理学改变,采用比色法测定髓过氧化物酶(MPO)活性和丙二醛(MDA)含量;采用ELISA法检测各组小鼠支气管肺泡灌洗液(BALF)中肿瘤坏死因子-α(TNF-α)含量和乳酸脱氢酶(LDH)活性.结果:美金刚胺预处理可降低LPS诱导的ALI小鼠肺湿/干重比值,减轻其肺组织病理学改变,减少肺组织中MPO和MDA的含量,同时可降低BALF中TNF-α含量以及LDH活性(均P＜0.05).结论:采用美金刚胺阻断NMDA受体可减轻LPS诱导的小鼠ALI,为临床治疗ALI提供了新思路.     

丙泊酚预处理通过活化PI3K/Akt通路减轻脂多糖诱导的大鼠急性肺损伤

目的 研究丙泊酚预处理对脂多糖诱导的大鼠急性肺损伤(ALI)是否有保护作用,这种保护作用是否和活化PI3K/Akt通路有关.方法 36只成年雄性SD大鼠被随机分为6组(n＝6):对照组(control组)、脂多糖(LPS)组、丙泊酚+LPS组、Wortmannin+丙泊酚+LPS组、丙泊酚组、Wortnannin组.检测各组大鼠支气管肺泡灌洗液(BALF)中蛋白、TNF-α和IL-6浓度,观察各组大鼠的肺水含量和肺组织的病理变化,以及肺组织中p-Akt的表达变化.另取36只大鼠,随机分为3组(n＝12):LPS组、丙泊酚+LPS组和Wortmannin+丙泊酚+LPS组,建立大鼠ALI模型,观察各组大鼠48 h的死亡率.结果 注射LPS后,大鼠BALF中的蛋白、TNF-α和IL-6的浓度明显升高,肺水含量显著增加(P＜0.05),肺组织破坏明显,肺组织中p-Akt表达减少.丙泊酚预处理降低肺组织损伤程度,使BALF中的蛋白渗出、TNF-α和IL-6释放减少(P＜0.05),肺水含量以及肺组织的病理损害减轻,肺组织p-Akt表达增多(P＜0.05).Wortmannin可减弱丙泊酚的保护作用,且单独使用Wortmannin对肺组织没有损害作用.丙泊酚+LPS组死亡率明显低于LPS组和Wortmannin+丙泊酚+LPS组(P＜0.05).结论 丙泊酚预处理可能通过诱导肺组织p-Akt表达,提高肺实质细胞对伤害刺激的耐受力,缓解LPS诱导的急性肺损伤.     

环氧化酶2抑制剂对大鼠机械通气所致肺损伤肺水代谢的影响

目的:探讨环氧化酶2 (COX-2)抑制剂对大鼠机械通气所致肺损伤(VILI)肺水代谢的影响.方法:健康成年雄性SD大鼠30只,体质量300～ 350 g,随机分为3组(n=10),对照组(TV组,潮气量8 mL/kg)、机械通气肺损伤组(HV组,潮气量40 mL/kg)、NS398预处理组(HV+NS398组).NS398预处理组于机械通气前30 min腹腔注射COX-2抑制剂NS398 8 mg/kg.于机械通气4h时处死大鼠,Western Blot法检测肺组织中水通道蛋白l(AQPl)、水通道蛋白5(AQP5)表达;检测血清及支气管肺泡灌洗液(BALF)中蛋白浓度,计算肺通透性指数(LPI);检测BALF中肿瘤坏死因子(TNF-α)浓度;计算肺组织湿/干重比(W/D).结果:与TV组相比,HV组BALF中TNF-α浓度增加,AQP1、AQP5表达降低(P＜0.05),LPI升高,肺组织W/D升高(P＜0.05);与HV组相比,HV+NS398组BALF中TNF-α浓度降低,AQP1、AQP5表达升高(P＜0.05),LPI及肺组织W/D降低(P＜0.05).结论:COX-2抑制剂可能通过上调AQP1、AQP5的表达,减轻肺水肿改善肺水代谢,从而减轻大鼠机械通气所致肺损伤.     

辛伐他汀对大鼠烟雾吸入性肺损伤中炎症反应的抑制作用

目的 研究辛伐他汀对大鼠烟雾吸手性肺损伤中炎症反应的抑制作用.方法 将18只SD大鼠(雌雄不限)随机分为正常组、盐水组、辛伐他汀组,建立烟雾吸手性肺损伤模型,模型建立后30 min及12 h,辛伐他汀组给予辛伐他汀溶液50 mg/kg灌胃,盐水组大鼠给予等量生理盐水灌胃,正常组大鼠正常饲养.于致伤后24 h取右上肺肺组织行病理检查并行病理学评分.经腹主动脉取全血离心留取上层血清,并行左侧支气管肺泡灌洗留取肺泡灌洗液(BALF),采用ELISA法检测血清及BALF中白介素(IL)-6、肿瘤坏死因子(TNF)-α的含量.取右下肺部分肺组织以Western blot法检测蛋白提取物中IL-6、TNF-α及胞质中NF-κB p65的蛋白表达情况.结果 光镜下观察正常组肺泡结构正常,盐水组肺泡间隔水肿,肺泡腔内可见大量的中性粒细胞浸润,而与盐水组相比,辛伐他汀组上述症状减轻且肺组织病理学评分降低(P＜0.05).盐水组、辛伐他汀组血清和BALF中IL-6、TNF-α的含量以及肺组织蛋白提取物中IL-6、TNF-α和NF-κB的表达均较正常组明显升高(P＜0.05).而与盐水组相比,辛伐他汀组大鼠血清和BALF中IL-6、TNF-α的含量以及肺组织蛋白提取物中IL-6、TNF-α及NF-κB p65的表达均降低(P＜0.05).结论 辛伐他汀通过抑制炎症介质的产生及炎症细胞的浸润,减轻吸手性肺损伤的炎症反应,对肺组织起到了一定的保护作用.     

机械通气诱导大鼠肺损伤病理及炎性细胞因子的变化

目的 探索不同机械通气压力对肺损伤病理及炎性细胞因子巨噬细胞炎性蛋白2(MIP-2)和肿瘤坏死因子α(TNF-α)的影响.方法 45只SD大鼠随机分成三组(每组15只):自主呼吸组、高容低频通气组(VT 34 mL,/kg,RR 30次/min)和低容高频通气组(VT 8 mL/kg,RR60 次/min).高容低频通气组和低容高频通气组通气时间120 min,通气期间临测平均动脉压(MAP)、血氧饱和度(SpO2)、体温(T)和血气分析.实验完成后抽取动脉血,处死大鼠取其肺叶组织,进行支气管肺泡灌洗液(BALF)提取,观察肺组织病理和肺湿/干重比值,分析动脉血细胞数、类型和细胞聚集反应,ELISA法检测动脉血和BALF中MIP-2和TNF-α浓度.结果 通气组大鼠肺组织均出现病理性改变,高容低频通气组较低容高频通气组明显;高容低频通气组大鼠肺湿/干重比值大于其他两组(P均＜0.05);三组细胞数、类型和细胞聚集反应结果比较无显著差异.三组血液和BALF中MIP-2和TNF-α仅浓度有显著差异(P均＜0.05),其中高容低频通气组动脉血和BALF中MIP-2和TNF-α浓度大于其他两组(P均＜0.05),而低容高频通气组水平大于自主呼吸组(P均＜0.05).结论 机械通气可诱导肺组织病理性损伤,其中大容量通气的肺组织损伤更为明显,血液和BALF中炎性细胞因子水平增高.     

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.