人参皂甙诱导的造血细胞内信号传递途径的研究

目的探讨人参皂甙（ＧＳ）刺激造血祖细胞增殖有关的细胞内信号传递途径。方法采用Ｎｏｒｔｈｅｒｎ印迹杂交法、电泳带移动阻滞实验、抗体胶结合移动实验和紫外放射交联实验。结果ＮｏｒｔｈｅｒｎＢｌｏｔ显示经ＧＳ诱导的人巨核细胞株ＣＨＲＦ２８８、Ｍｅｇ０１和ＭＯ７ｅ细胞的ＧＡＴＡ２ｍＲＮＡ水平增高,分别是未经处理细胞的１．８４,２．４３和１．５２倍。但ＧＡＴＡ１ｍＲＮＡ表达水平低,且ＧＳ处理前后也无明显变化。电泳带移动阻滞实验提示ＧＳ诱导的细胞核内ＧＡＴＡ转录调控蛋白与特定的ＤＮＡ序列结合的活性增高。抗体胶结合移动实验证实与ＤＮＡ结合的主要成分为ＧＡＴＡ２蛋白,紫外放射交联实验确定该复合物的相对分子质量约为５０×１０３,符合ＧＡＴＡ２转录调控蛋白。结论ＧＳ诱导细胞内的信号传递途径与转录因子ＧＡＴＡ２有关,ＧＡＴＡ２有介导ＧＳ刺激造血细胞增殖的作用。     

Characteristics and smoking patterns of intermittent smokers

Current models of smoking and dependence assume a need to smoke at regular intervals to maintain nicotine levels, yet about 25% of adult smokers do not smoke daily. This subset of intermittent smokers (ITS) has gone largely unexamined. In this study, we describe the demographics, smoking history, and smoking behavior of ITS (n = 282; 50.2% male) in comparison to daily smokers (DS; n = 233; 60.7% male). Within ITS, we also compare "converted" ITS (CITS), who had previously smoked daily, with "native" ITS (NITS). On average, ITS were 34.66 years of age, and had smoked 42,850 cigarettes in the course of an average of 18 years of smoking. They smoked an average of 4.38 days per week, consuming 4.39 cigarettes a day on smoking days, and demonstrated considerable day-to-day variability in cigarette consumption. Almost half of ITS had Fagerstrom Test of Nicotine Dependence scores of 0, indicating no dependence. Compared to DS, ITS were more likely to cite alcohol drinking, socializing, and being with other smokers as common contexts for smoking, and they also more often cited being angry or stressed. Data suggested that ITS' behavior was not explained by use of other nicotine products nor by economic constraints on smoking, nor by differences in psychological adjustment. Within ITS, CITS were heavier, more frequent, and more dependent smokers. In many respects, CITS were intermediate between NITS and DS. ITS show distinct patterns of smoking behavior that are not well explained by current models of nicotine dependence.     

Antimicrobial peptides: a potential role in ocular therapy

Bacterial pathogens are often involved in contact lens‐related adverse responses. This study aimed to find antimicrobial peptides and proteins that effectively eradicate or inhibit ocular bacteria. The antimicrobials were screened against Gram‐ negative and Gram‐positive bacteria originating from ocular sources. The viability of these ocular bacteria was measured after exposure to the peptides and proteins. Two conditions were used to grow bacteria, low nutrient phosphate‐buffered saline and high nutrient tryptone soya broth. Samples were taken at different times up to 48 h. In low nutrient conditions, protamine was found to be the most effective against all strains. Melittin was very effective against all strains except Serratia and one Pseudomonas isolate which were partially affected. In high nutrient condition, only melittin was effective in killing Staphylococcus aureus. Protamine and the combination of protamine and melittin had the greatest effect in eradicating the bacteria tested in low nutrient condition. Protamine alone and its combination with melittin may have potential therapeutic agents for ocular infections in an era of emerging antibiotic resistance.     

Serum interleukin 2 receptor levels in childhood acute lymphoblastic leukemia

The clinical significance of interleukin 2 receptor (IL2R) concentrations in serum was determined for 344 children with newly diagnosed acute lymphoblastic leukemia (ALL). Serum levels of IL2R in patients (267 to 80,000 U/mL, median 2,007 U/mL) were significantly higher than normal control values (170 to 738 U/mL, median 347 U/mL) (P less than .0001). Measurements in cases of T cell ALL were lower than in the non-T, non-B cases (P = .02). Among the 264 patients with non-T, non-B ALL, but not in those with T cell disease, higher serum IL2R levels (greater than 2,000 U/mL) were associated with a poorer treatment outcome (P = .04). In a multivariate analysis, serum IL2R level contributed independent prognostic information beyond that conveyed by leukocyte count, race, and age (P = .04). One explanation for these results is that soluble IL2R competes with normal lymphocyte- integrated IL2R for the ligand and thus could suppress host antitumor immunity.     

Identification of a membrane glycoprotein associated with haemopoietic progenitor cells

A monoclonal antibody (3C5) is described which selectively binds to progenitor cell populations in human bone marrow and foetal liver. Mature, lymphoid (T,B) colony forming cells do not express the antigen. The antibody identifies a cell surface glycoprotein of mol. wt approximately 100,000 which might have an important regulatory role in early haemopoietic differentiation.