请选择 进入手机版 | 继续访问电脑版
设为首页收藏本站

老西部英语

 找回密码
 立即注册

只需一步,快速开始

[大学生论坛]:女性的生育力保存

5

主题

5

资源

30

积分

新手上路

Rank: 1

积分
30
Tsohoiyen 发表于 2019-1-4 21:41:37 | 显示全部楼层 |阅读模式
In recent years, the demand for fertility preservation for oncologic and nononcologic reasons, as well as personal reasons, has increased dramatically, and meeting this demand will prove a major challenge in the coming years. Currently, embryo cryopreservation and mature-oocyte cryopreservation after ovarian stimulation are the only methods of fertility preservation endorsed by the American Society for Reproductive Medicine. However, many experts believe that there is now enough evidence to support the use of ovarian-tissue cryopreservation as a valid and effective technique rather than as an experimental approach.
Of all the available means of fertility preservation,1 oocyte cryopreservation by means of vitrification (very rapid freezing) provides the highest yield, not only for women with benign diseases or those seeking fertility preservation for personal reasons but also for women with cancer (if treatment can be postponed). Ovarian-tissue cryopreservation is specifically indicated for adolescents and women in whom cancer treatment cannot be postponed. This review focuses on the indications for and results of these two techniques of fertility preservation.
近年来,由于肿瘤和非肿瘤原因以及个人原因对生育力保存的需求急剧增加,满足这一需求将在未来几年成为重大挑战。目前,只有胚胎冷冻保存和促排卵后的成熟卵母细胞冷冻保存是美国生殖医学学会(American Society for Reproductive Medicine)认可的生育力保存方法。然而,许多专家认为,现在有足够的证据支持将卵巢组织冷冻保存作为正规有效的生育力保存技术,而不仅仅是作为一种实验性方法。
在所有可用的生育力保存手段中,应用玻璃化冷冻(极速冷冻)方法的卵母细胞冷冻保存效果最好,不仅对患良性疾病或者因个人原因选择保存生育力的妇女适用,而且对患癌症的妇女(可暂缓治疗的)亦同样适用。卵巢组织冷冻保存则专门针对青少年和癌症治疗不能推迟的患者。本综述重点阐述这两种生育力保存技术的适应证和结果。
Ovarian Reserve
The term ovarian reserveis typically used to refer to the population of primordial follicles. Initiation of the resting primordial-follicle reserve begins in the fetus, when 100 to 2000 primordial germ cells colonize the genital ridges and enter a massive proliferation process that results in 7 million potential oocytes at midgestation. In the human ovary, approximately 85% of these potential oocytes are lost before birth. The decline in the number of follicles continues throughout reproductive life, during which time approximately 450 ovulatory cycles occur, with the majority of follicles undergoing atresia during their growth phase. The serum level of antimüllerian hormone, which is correlated with the number of primordial follicles but is not a direct product of these follicles, can be used to estimate the reproductive life span.
卵巢储备
“卵巢储备”通常指原始卵泡的数目。处于休眠期的储备原始卵泡的激活始于胎儿期,届时1002,000个原始生殖细胞会定殖于生殖嵴并开始大量增殖,至妊娠中期即发展为700万个潜在的卵母细胞。在人卵巢中,大约85%的潜在卵母细胞会在出生前就丢失,且卵泡数量在整个育龄期仍持续下降,在此期间有大约450次排卵期,伴随的是大多数卵泡在其生长阶段期间发生闭锁。抗苗勒管激素的血清水平与原始卵泡数量相关,但不是这些卵泡的直接产物,其可用于评估生育年限。
Indications for Fertility Preservation.
Fertility preservation remains a challenge, particularly in the case of hematologic cancers (Hodgkins lymphoma, non-Hodgkins lymphoma, and leukemia) and breast cancer. These cancers constitute the most frequent indications for fertility preservation, since chemotherapy (especially with alkylating agents), radiotherapy, surgery, or a combination of these treatments can induce premature ovarian insufficiency in some circumstances1,6-10 (Table 1). The ovaries are very sensitive to cytotoxic drugs, especially alkylating agents, which are likely to cause gonadal dysfunction.6,7,11,12 Cyclophosphamide is the alkylating agent that causes the most damage to oocytes and granulosa cells, and it does so in a dose-dependent manner. In a recent review,13 it was reported that the North American Childrens Oncology Group considers the risk of premature ovarian insufficiency to be highest with busulfan administered at a dose of at least 600 mg per square meter of body-surface area, cyclophosphamide at a dose of at least 7.5 g per square meter, or ifosfamide at a dose of at least 60 g per square meter, but an international multidisciplinary panel reached no consensus on this matter.
Pelvic radiotherapy is also known to cause premature ovarian insufficiency, since exposure to 5 to 10 Gy is toxic to oocytes. Indeed, the human oocyte is very sensitive to radiation a dose of less than 2 Gy is estimated to be sufficient to destroy 50% of primordial follicles.
Ultimately, the probability that premature ovarian insufficiency will develop after chemotherapy or radiotherapy is related to the ovarian reserve. This reserve (the population of primordial follicles) can vary enormously from one woman to the next.
恶性疾病
生育力保存仍然是一个挑战,特别是对于血液系统癌症(霍奇金淋巴瘤、非霍奇金淋巴瘤和白血病)和乳腺癌患者。由于化疗(特别是烷化剂)、放疗、手术或联合治疗在某些情况下可能导致早发性卵巢功能不全,因此上述癌症是生育力保存的最常见适应证(表11,6-10。卵巢对细胞毒性药物,特别是对可能引起性腺功能障碍的烷化剂非常敏感6,7,11,12。环磷酰胺是对卵母细胞和颗粒细胞造成最大损伤的烷化剂,且损伤程度与用药剂量相关。据近期的一次综述报道,北美儿童肿瘤研究组(North American Childrens Oncology Group)认为以下剂量的药物治疗时发生早发性卵巢功能不全的风险最高:600 mg/m2或更大剂量的白消安,7.5 g/m2或更大剂量的环磷酰胺,以及60 g/m2或更大剂量的异环磷酰胺13。但国际上多学科专家小组在此问题上未达成共识。
盆腔放疗亦同样被认为可引起早发性卵巢功能不全,因为510 Gy剂量的射线对卵母细胞有毒性作用。事实上,人类卵母细胞对射线非常敏感,估计小于2 Gy的剂量足以破坏50%的原始卵泡。
最终,化疗或放疗后发生早发性卵巢功能不全的概率与卵巢储备有关,而该储备(原始卵泡的数目)存在很大的个体差别。
BENIGN CONDITIONS
Fertility preservation should also be offered to women with certain benign conditions that carry the risk of premature ovarian insufficiency. Many autoimmune and hematologic conditions sometimes require chemotherapy, radiotherapy, or both and sometimes even bone marrow transplantation (Table 1). Other conditions can also impair future fertility, such as the presence of bilateral ovarian tumors, severe or recurrent ovarian endometriosis, and recurrent ovarian torsion.
Ovarian endometriomas lead to reduced ovarian reserve. Local intraovarian inflammation induced by the presence of endometriomas has been shown to trigger follicle burnout,characterized by activated follicular recruitment with subsequent atresia. Moreover, increasing evidence shows that performing cystectomy on endometriomas may cause considerable damage to the ovarian reserve, so fertility preservation should certainly be contemplated in case of recurrence after surgery.
Turners syndrome and a family history of premature ovarian insufficiency are additional indications for fertility preservation1 (Table 1). There is compelling evidence that certain forms of premature ovarian insufficiency have a genetic cause.
良性疾病
生育力保存的对象除恶性疾病患者外,还包括患某些良性疾病,因此有早发性卵巢功能不全风险的妇女。许多自身免疫病和血液系统疾病有时需要化疗、放疗或两者联合治疗,有时甚至需要骨髓移植(表1)。此外其他疾病如存在双侧卵巢肿瘤、重度或复发性卵巢子宫内膜异位症和复发性卵巢扭转等都会损伤未来的生育力。
卵巢子宫内膜异位症可导致卵巢储备减少。由子宫内膜异位症引起的局部卵巢内炎症已被证明可使卵泡“燃尽”,其特征为活化的卵泡募集后出现卵泡闭锁。此外,越来越多的证据表明,在子宫内膜异位灶上进行囊切术可能会对卵巢储备造成相当大的损害,因此在术后复发的情况下,有必要考虑生育力保存。
Turner综合征和早发性卵巢功能不全家族史也是生育力保存的适应证(表1)。有力证据表明某些形式的早发性卵巢功能不全有遗传原因。
AGE-RELATED FERTILITY DECLINE
The largest group of women seeking fertility preservation consists of those who wish to postpone childbearing for various personal reasons; the biggest threat to their fertility is age. Women are increasingly seeking time outuntil they reach the right stage in their life to have a baby, often postponing childbearing because of the lack of a partner, the lack of a stable partner, or career or financial issues. The age at which women attempt their first pregnancy has been steadily rising during the past 40 years
与年龄相关的生育力下降
在寻求生育力保存的妇女中,很大一部分人由于多种个人原因希望暂缓生育,这种情况下对生育力威胁最大的是自身年龄。越来越多的女性会推迟生育时间,直到适合要孩子的人生阶段,此类妇女大多由于单身、缺乏稳定伴侣或出于事业或经济上的考虑而暂缓生育。过去40年来,妇女首次尝试怀孕的平均年龄一直在稳定推迟。

https://www.nejm.org/doi/full/10.1056/NEJMra1614676
2015级商务英语曹凯茵 3151204004

友荐云推荐
评论

使用道具 举报

QQ|关于我们|联系我们|网络条款|建议反馈|小黑屋|老西部英语 ( 版权所有 粤ICP备11103350号  

GMT+8, 2019-8-23 04:28 , Processed in 0.162315 second(s), 27 queries .

Powered by Discuz! X3

© 2001-2013 Comsenz Inc.