This is essentially like a placebo treatment to show the natural history of the disease.

这基本上就像安慰剂治疗，显示疾病的自然发生过程。

The size of oral lesion decreased in 67.8% of the patients in the treated group while only 16.9% in the placebo treatment group.

临床治疗组有67.8%的患者白斑病损缩小，而对照组仅16.9%的患者白斑病损缩小。

The study advises doctors to only prescribe placebos if the patient has a minor illness and if it seems likely that a placebo treatment will be successful.

该调查对此建议医生仅对那些患有小病和安慰剂能起到有效作用的病人使用安慰剂。

For this study, researchers compared animals that received placebo treatment with those that received only protective neurotrophic factors secreted by stem cells and those that had a transplant.

在这项研究中，研究者将接受安慰剂的动物，与仅接受由神经干细胞分泌的保护性神经营养因子以及接受移植的动物进行了对照。