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ABSTRACT: Renal impairment is one of frequent and serious complications in patients with multiple myeloma (MM) and is associated with a higher incidence of infections and early death rate. The catalytic activity of Bence Jones proteins (BJP) affects the clinical processes of patients with MM, and can lead to renal impairment. Scientists point out that BJP have peptidolytic and nucleolytic activity, which can lead porcine kidney proximal tubule (LLC-PK1) to apoptosis in vitro experiments. By treating the cytotoxic BJP with serine protease inhibitor (DFP), BJP lost not only their catalytic activity, but also the cytotoxic effects. Therefore, further research on BJP will helpful to understand the pathogenesis of renal impairment in MM patients and may provide a new idea and measure for the treatment of MM with renal impairment. This article reviews the basic research and progress on the catalytic activity of BJP.
Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology 06/2012; 20(3):796-800.
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ABSTRACT: This study was purposed to investigate the relationship between the catalysis of Bence Jones protein (BJP) in urine of patients with multiple myeloma(MM) and toxicity on the renal proximal tubular cells in vitro, and to explore the potential mechanism for the toxicity of BJP to renal impairment in patients with MM. The Michaelis-Menten constant (K(m)) and catalytic constant (k(cat)) of the amidase activity of BJP was calculated by Hanes equation. The LLC-PK1 cells were cultured with different concentration of BJP for 24 h, then proliferation of the cells were determined by MTT method and apoptosis were determined by flow cytometry. The results showed that the BJP from the MM patients with renal impairment significantly inhibited cell proliferation, as compared with that from MM patients without renal impairment. The BJP with higher k(cat) had higher toxicity to LLC-PK1 cells. BJP could induce apoptosis and necrosis of LLC-PK1 cells when reached a certain concentration and this effect enhanced with increase of BJP concentration. It is concluded that the catalysis of BJP and its toxicity to renal tubular epithelial cells has a positive correlation, and toxic effect of BJP on renal tubular epithelial cells results from inhibiting proliferation and inducing apoptosis and necrosis of the cells, which may be one of renal impairment mechanisms in MM patients.
Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology 03/2012; 20(2):339-43.
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ABSTRACT: To evaluate the diagnostic and therapeutic significance of serum free light chain (sFLC) in primary systemic(AL) amyloidosis.
Twenty-five patients with AL amyloidosis, including 18 men and 7 women with a mean age of 54 (47 - 77) years old, were enrolled from October, 2005 to May, 2010. sFLC was measured by immunoturbidimetric assay. The type of monoclonal light chain was judged upon sFLC κ/λ and its sensibility was compared with serum immunofixation and immunohistochemical analysis. Four patients were treated with M(T)D (melphalan/thalidomide,and dexamethasone), one with VD (velcade and dexamethasone) and four with high-dose melphalan followed by autologous stem cell support. The changes of sFLC were serially determined before and after treatment.
Among the 25 patients with AL amyloidosis, two were κ light chains of precursor protein and 23 were λ light chains. Mean plasma cell in bone marrow was 3.5% (0 - 15%). Nineteen (76%) patients had abnormal elevated sFLC and abnormal κ/λ ratios, and 17(68%) patients with immunofixation positive. The sFLC test had similar sensitivity as serum immunofixation (P = 0.727). Twenty-one (84%) patients were shown to have either κ or λ immunoreactive amyloid deposits on biopsied tissues. The sFLC test combined with serum immunofixation allowed the M protein to be detected in 22 (88%) patients. The positive rates of immunohistochemical analysis combined with sFLC test and/or serum immunofixation were 96%. Four patients with hematologic response showed obvious improvement in visceral organ involvement, but illness of 5 patients without hematologic response kept stable or progressed.
sFLC test is a sensitive qualitative and quantitative method to detect M protein. Preliminary data show the patients with obvious sFLC level decrease and/or κ/λ recovery to normal may have a high percentage of improved organs function. sFLC is critical index in diagnosing AL amyloidosis, which might help efficacy assessment.
Zhonghua nei ke za zhi [Chinese journal of internal medicine] 05/2011; 50(5):404-7.
