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.     

Carcinoids of the gastrointestinal tract

Carcinoids are tumors of the diffuse endocrine system. They occur most frequently in the gastrointestinal tract. Although they are considered malignant, their biologic behavior varies. The radiologic and pathologic appearances of gastric, duodenal, ileal, appendiceal, and rectal carcinoids are presented.     

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...     

The World Health Organization's Histological Classification of Lung Tumors: a comparison of the first and second editions

Revision of the WHO Histological Classification of Lung Tumors of 1967 has resulted in the 1981 publication of the second edition. The main features of the revisions have been summarized. Squamous cell carcinoma (epidermoid carcinoma) has the same definition as in the original version, ie, the identification of keratin and/or intercellular bridges by light microscopy. Three degrees of histological differentiation have been described. Dysplasia and carcinoma in situ have been discussed. Small cell carcinoma has been divided into oat cell carcinoma, an intermediate cell type and a category for oat cell carcinomas combined with other major types. Adenocarcinoma includes the acinar, papillary and bronchiolo-alveolar forms, and the solid carcinomas with mucus formation (previously part of the large cell carcinoma group). A number of less common tumors and tumor-like lesions have been defined. None of the changes in the revision are considered to be a major departure from the original classification. This is intended in order to preserve comparability between data collected with each edition. The need for utilizing standardized nomenclature, diagnostic criteria, and tabulation formats is stressed.     

TNM classification of malignant tumors. A comparison between the new (1987) and the old editions

A major revision of the tumor, nodes, metastasis (TNM) classification has been published. It eliminates previous differences between the International Union Against Cancer (UICC) and American Joint Committee on Cancer (AJCC) versions. It also updates existing site classifications and adds chapters on previously unclassified tumors. This article summarizes the major changes from the past to the present editions of the TNM classification.