Modeling the variability of shapes of a human placenta.
Modeling the variability of shapes of a human placenta.
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DOI：
10.1016/j.placenta.2008.06.005
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发表时间：
2008-09
期刊：
影响因子：
3.8
通讯作者：
Thorp, J.
中科院分区：
文献类型：
--
作者：
Yampolsky, M.;Salafia, C. M.;Shlakhter, O.;Haas, D.;Eucker, B.;Thorp, J.
胎盘通常是圆形-椭圆形的，但“不规则”的形状也很常见。在围产期合作项目的数据中，不规则形状与胎盘重量的出生体重较低相关，表明圆形胎盘功能改变。(I)使用基于扩散限制聚集（一种用于生成高度分支分形的公认模型）的胎盘血管生长的3-D单参数模型，在分支密度生长参数固定或扰动为模型生长的5-7%或50%的情况下运行模型。(II)在1207个胎盘周长的详细测量数据集中，从脐带插入和形状的质心（生物学上的任意点）计算胎盘形状的径向标准差。这两个进行了比较，观察到的标度指数和克莱伯标度指数（0.75），血管分形运输系统被认为是最佳的差异。斯皮尔曼等级相关性认为p<0.05显著。(I)未受干扰的，随机值的增长参数创建圆形椭圆形分形形状。模型增长5-7%时的扰动会产生多叶形状，而模型增长50%时的扰动会产生“星形”分形。(II)脐带周长的径向标准差（但不是质心）与Kleiber指数的差异相关（p=0.006）。动态DLA模型通过改变分形分支密度再现了多叶和“星星”状胎盘。我们认为：（1）不规则的胎盘轮廓反映了基础胎盘分形血管网的变形，（2）胎盘轮廓的不规则性表明血管树的分支结构不理想，（3）这解释了围产期合作项目中观察到的非圆形/椭圆形胎盘的出生体重较低。
Placentas are generally round-oval in shape, but “irregular” shapes are common. In the Collaborative Perinatal Project data, irregular shapes were associated with lower birth weight for placental weight, suggesting variably shaped placentas have altered function. (I) Using a 3-D one-parameter model of placental vascular growth based on Diffusion Limited Aggregation (an accepted model for generating highly branched fractals), models were run with a branching density growth parameter either fixed or perturbed at either 5-7% or 50% of model growth. (II) In a data set with detailed measures of 1207 placental perimeters, radial standard deviations of placental shapes were calculated from the umbilical cord insertion, and from the centroid of the shape (a biologically arbitrary point). These two were compared to the difference between the observed scaling exponent and the Kleiber scaling exponent (0.75), considered optimal for vascular fractal transport systems. Spearman’s rank correlation considered p<0.05 significant. (I) Unperturbed, random values of the growth parameter created round-oval fractal shapes. Perturbation at 5-7% of model growth created multilobate shapes, while perturbation at 50% of model growth created “star-shaped” fractals. (II) The radial standard deviation of the perimeter from the umbilical cord (but not from the centroid) was associated with differences from the Kleiber exponent (p=0.006). A dynamical DLA model recapitulates multilobate and “star” placental shapes via changing fractal branching density. We suggest that (1) irregular placental outlines reflect deformation of the underlying placental fractal vascular network, (2) such irregularities in placental outline indicate sub-optimal branching structure of the vascular tree, and (3) this accounts for the lower birth weight observed in non-round/oval placentas in the Collaborative Perinatal Project.
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