Invasion of erythrocytes by Plasmodium falciparum malaria parasites: evidence for receptor heterogeneity and two receptors

Plasmodium falciparum malaria parasites with different capabilities of invading sialic acid-deficient erythrocytes were identified. Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase-treated and Tn erythrocytes twice as efficiently as Thai-2 parasites cultured in normal erythrocytes and seven to ten times more efficiently than a cloned line of Camp parasites cultured in normal erythrocytes. All three parasite lines required sialic acid for optimal invasion, but Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase- treated erythrocytes with 45% efficiency whereas Camp parasites invaded neuraminidase-treated erythrocytes with less than 10% efficiency. P falciparum malaria parasites probably possess two receptors: one that binds to a sialic acid-dependent ligand and another that binds to a sialic acid-independent ligand. Parasites may differ in the quantity or affinity of their receptors for the sialic acid-independent ligand.     

Expression of bcl-xL can confer a multidrug resistance phenotype

It has been suggested that genes that regulate apoptotic cell death may play an important role in determining the sensitivity of tumor cells to chemotherapy. We have recently cloned a member of the bcl-2 family, bcl- x. To test whether bcl-XL expression affects the sensitivity of tumor cells to chemotherapy, we have created stable cell lines overexpressing bcl-XL and have tested these cells for resistance to cell death induced by metabolic inhibitors and chemotherapeutic agents. Bcl-XL expression dramatically reduces the cytotoxicity of bleomycin, cisplatin, etoposide, vincristine, hygromycin B, and mycophenolic acid for up to 4 days in culture. Bcl-XL does not prevent cells from undergoing cell cycle arrest in response to these drugs, but rather prevents treated cells from undergoing apoptosis. Cell-cycle analysis on cells treated with the chemotherapeutic agents bleomycin, cisplatin, etoposide, and vincristine, show that the drugs cause growth arrest in different positions within the cell cycle. Bcl-XL expressing cells treated with chemotherapeutic drugs retain their proliferative ability after the drugs are removed. Interestingly, vincristine-treated cells expressing bcl-XL become polyploid after drug removal. These data show that bcl-XL protects cells from a wide variety of apoptotic stimuli, acts in multiple positions within the cell cycle, and confers a multidrug resistance phenotype. The ability of bcl-XL to prevent apoptotic cell death in response to chemotherapy-induced DNA damage and cell-cycle arrest may contribute to the accumulation of chromosomal aberrations within tumors. The expression of bcl-XL in tumor cells is likely to be an important indicator of chemotherapeutic efficacy.     

胆碱能M受体拮抗剂：2α－（2＇，2＇－二取代基－2＇－羟基乙氧基）托品烷光学异构体合成

胆碱能Ｍ受体拮抗剂：２α－（２＇，２＇－二取代基－２＇－羟基乙氧基）托品烷光学异构体合成王林，恽榴红，张其楷（军事医学科学院毒物药物研究所，北京１００８５０）目前临床所用托品类抗胆碱药一般为３位取代托品酯类衍生物，这类药物作用较广泛，但选择性不高。Ａ...     

Total lipids, cholesterol, phospholipids and inorganic phosphorus in the amniotic fluid of premature infants.

Total lipids, total cholesterol, phospholipids and inorganic phosphorus were determined in the amniotic fluid of 36 normal and 12 premature neonates. Total lipids, phospholipids and cholesterol were significantly decreased in the premature patients and the extent of decrease was more pronounced in patients who developed respiratory distress syndrome. On the other hand, inorganic phosphorus content of the amniotic fluid was within the normal range.     

肾康宁片中黄芪甲苷的薄层扫描法测定

目的:建立肾康宁片中黄芪甲甙含量测定方法。方法:双波长薄层扫描法,经水饱和正丁醇液冷浸超声提取,再上D101大树脂纯化,以氯仿-甲醇-水(65:30:10)下层液为展开剂,检测波长为520nm,参比波长为700nm。结果:平均加样回收率为97.8％(RSD=1.4％,n=6),标准曲线r=0.9996。结论:方法结果可靠、操作简单,可作为肾康宁片的质量控制标准。