tailieunhanh - Parkinson disease and related disorders part - part 9

Với một số thông tin thêm kỹ thuật, giống như sắt hóa trị và / hoặc xác định các ràng buộc hợp chất sắt hoặc nồng độ của các yếu tố khác trong các mô, có thể thu được. Nồng độ sắt đo bằng các kỹ thuật khác nhau mang lại kết quả rất khác nhau - khác nhau | 494 A. FRIEDMAN ET AL. . Iron concentration in normal and parkinsonian substantia nigra Postmortem studies SN has been known for its high iron concentration since 1958 when Hallgren and Sourander published the results of a quantitative assessment by colorimetry of iron concentration in normal human brains. These authors measured 52 samples of SN. The average iron concentration in SN calculated from these measurements was mg g wet tissue which was higher than that measured by these authors in human liver mg g . Since the late 1960s many researchers tried to assess the iron concentration in parkinsonian and normal SN. The normal SNs were usually obtained from control subjects who died without any clinical or pathological signs of neurodegenerative disease. The results obtained in these measurements on postmortem SN are summarized in Tables and and Figs. and . The data presented are based on all available papers published up to the end of 2004 and only include references to papers in which data obtained from certain experiments were described for the first time. As shown in these tables and figures iron concentrations were assessed in postmortem tissue by different techniques. Each technique has its advantages and disadvantages depending on several factors such as the tissue preparation necessary for carrying out the measurement the amount of tissue needed for the measurement and the sensitivity of the method. With some techniques additional information like the iron valence and or the identification of iron-binding compounds or the concentration of other elements in the tissues can be obtained. The iron concentrations measured by different techniques yield very different results - ranging from 48 to 480 mg g for wet control tissues and from 85 to 280 mg g for wet PD tissues Table and Fig. . The lowest concentrations were measured by spectrophotometry. Spectrophotometry requires homogenization of samples in