DiResta G R, Lee J B, Arbit E
Nuclear Medicine Research Laboratory, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
J Neurosci Methods. 1991 Oct;39(3):245-51. doi: 10.1016/0165-0270(91)90103-7.
In this paper we introduce and characterize pycnometry, a method used to measure fluid density, for determining a tissue's specific gravity. It uses a 2-ml glass pycnometer filled with distilled water to determine a tissue sample's displacement volume. The tissue's density is determined when it's weight is divided by this volume and specific gravity is computed by dividing the tissue density by the density of water. Pycnometry was validated using pre-calibrated glass, specific gravity standards over the range 1.03-1.26, and compared to the density gradient method using rat brain tissue. We observed that the specific gravity values obtained using pycnometry were highly correlated with the specific gravity standards (slope = 1.0107, r = 0.996) and with the density gradient column when tissue volumes larger than 0.120 ml were used with the pycnometer (slope = 1.0707, r = 0.9826). Good correlation was also observed between percent water content values computed using the Nelson equation with pycnometry or density gradient specific gravity values versus the measured percent water content values obtained with the wet weight/dry weight method. Pycnometry is an accurate, reproducible technique to measure tissue specific gravity and brain edema and is best suited for use in a laboratory that engages sporadically in brain edema measurement.
在本文中，我们介绍并描述了比重瓶法，这是一种用于测量流体密度以确定组织比重的方法。它使用一个装有蒸馏水的2毫升玻璃比重瓶来确定组织样本的排液体积。当组织重量除以该体积时可确定其密度，而比重则通过将组织密度除以水的密度来计算。使用预先校准的玻璃、比重范围在1.03至1.26之间的比重标准物对比重瓶法进行了验证，并与使用大鼠脑组织的密度梯度法进行了比较。我们观察到，当使用比重瓶处理体积大于0.120毫升的组织时，用比重瓶法获得的比重值与比重标准物高度相关（斜率 = 1.0107，r = 0.996），与密度梯度柱也高度相关（斜率 = 1.0707，r = 0.9826）。在用比重瓶法或密度梯度比重值通过尼尔森方程计算得到的含水量百分比值与通过湿重/干重法测得的含水量百分比值之间也观察到了良好的相关性。比重瓶法是一种准确、可重复的测量组织比重和脑水肿的技术，最适合偶尔进行脑水肿测量的实验室使用。
