用Lyman NTCP模型分析原发性肝癌三维适形放疗引起的放射性肝病

目的建立原发性肝癌三维大分割适形放疗Lyman NTCP模型的参数和探讨放射性肝病的影响因素。方法109例患者进行大分割三维适形放疗,其中93例患者肝硬化Child-Pugh分级A级,16例为B级。患者每星期治疗3次,每次间隔48h,(4．8±0．5)Gy/次,平均剂量(53．5±5．5)Gy。用最大拟然比方法分别得到Child-A和Child-B患者Lyman模型中的NTCP参数。结果共有17例发生放射性肝病,发生在Child-A组8例,Child-B组9例。多因数分析表明,肝硬化分级程度是与放射性肝病相关的独立因素(P=0．000)。所有患者的NTCP参数为n=1．1,m=0．35,TD_(50) (1)=38．5Gy；Child-A级为n=1．1,m=0．28,TD_(50)(1)=40．5Gy；Child-B级为n=0．7,m=0．43,TD_(50)(1)=23Gy。结论肝硬化分级是预测放射性肝病发生的危险因子。Child-B患者进行适形放疗易引起放射性肝病。     

人肝门部胆管癌转移动物模型的建立及生物学特性研究

目的利用人肝门部胆管癌细胞系（FRH-0201）接种裸鼠脾脏，建立肝、肺转移模型。方法将FRH-0201细胞系（120代）接种于7只Balb／c裸小鼠脾脏。出现转移时，将转移瘤行组织病理学及超微结构观察。将转移的肿瘤行细胞培养，再次接种裸鼠脾脏，观察转移成瘤情况。结果脾脏局部成瘤率为100％（7／7），转移瘤发生率14．3％（1／7）。转移瘤细胞再次接种于裸小鼠脾脏，转移发生率100％。转移瘤电镜显示典型恶性细胞特征。转移瘤细胞染色体众数19条，主流范围18～44条。结论该实验所建立的肝门部胆管癌转移瘤，符合恶性肿瘤的特点，与人肝门部胆管癌生物学特性一致。     

20世纪后半叶美国高等医学教育改革历程

美国现代高等医学教育模式的确立是以20世纪初Flexner报告发表为开端的。第二次世界大战前，现代高等医学教育体系已基本完善，并经历了二战的考验。二战后，随着社会和医学发展，美国高等医学教育一直在进行着改革。按照时间顺序在50年代、60年代以及70、80年代进行了改革。分析历次改革的背景、主要内容及改革的特点特别对指导20世纪80年代后医学教育改革的纲领性文件——GPEP报告进行详细阐述，包括GPEP报告的内容、作用以及与Flexner报告的对比分析。通过回顾与分析，对美国医学教育改革历程中的成功经验和不足之处进行梳理，为我国正在进行的高等医学教育改革提供借鉴与参考。     

制作角膜缘干细胞完全缺乏动物模型的新方法

目的提出一种新的角膜缘干细胞完全缺乏模型制作方法,为干细胞缺乏疾病的治疗性研究提供可靠的模型。方法利用9mm环钻划界,板层切除角膜组织,通过临床评分、印迹细胞学、组织病理及免疫组织化学验证模型的成功。结果板层切除术后30~45d,模型眼角膜混浊、上皮缺损、大量新生血管长入,印迹细胞学可见PAS( )的杯状细胞,组织病理学检查上皮符合结膜细胞表型,免疫荧光染色可见结膜杯状细胞特异性标志MUC5AC阳性表达。结论环钻划界加板层切除法为一种可靠、有效的角膜缘干细胞完全缺乏模型制作方法。     

Strain difference in tolerance to low-temperature treatment of fertilized mouse oocytes

Background and Aims:  The aim of this study was to determine which mouse strains exhibit tolerance to cooling when fertilized oocytes have been stored at 4°C.
Methods:  In-vitro -fertilization-derived oocytes of eight mouse strains were incubated at 4°C in 20 mmol/L Hepes-potassium modified simplex optimized medium (KSOM) medium for 0, 24, 48, 60 or 72 h, and then returned to normal culture conditions at 37°C in KSOM medium. The rates of development of cultured oocytes into blastocysts and cell numbers of blastocysts were examined. In some cases, a Comet assay was carried out to evaluate DNA damage. In addition, the effects of β-mercaptoethanol on the development of the 4°C-treated oocytes were assessed.
Results:  Of the eight strains tested, BDF1, B6C3F1 and FVB/N strains exhibited relatively higher degrees of tolerance to 4°C treatment and approximately 90%, 83% and 78% of oocytes treated at 4°C for 48 h developed to morphologically normal blastocysts, respectively. Comet assay revealed no clear DNA damage in oocytes treated at 4°C. Treatment with β-mercaptoethanol failed to improve the in vitro survival rate of low-temperature-treated oocytes.
Conclusion:  Strain differences were observed in tolerance to cooling treatment when fertilized oocytes were temporarily treated with 4°C, although the reasons for this remain unclear. (Reprod Med Biol 2006; 5 : 43–50)     

Therapeutic effect of antimicrobial drugs against experimental infections due toYersinia pestis in mice

Although there are effective antibacterial agents against plague, newer antibacterial agents have been developed which show more potent activity against other bacterial organisms, but have not been tested againstYersinia pestis. A strain ofYersinia pestis was selected (no. 22; National Institute of Infectious Diseases, Tokyo, Japan) that caused a systemic infection in mice.Y. pestis no. 22 was intraperitoneally inoculated into DDY-strain mice, and 13 oral or 6 injectable antibacterial drugs given to the infected mice at varying doses 1 and 24 hours after infection. Levofloxacin, sparfloxacin and ofloxacin were the most effective oral agents against the infection, and prulifloxacin and pazufloxacin were also effective but to a lesser extent. Also, gentamicin and arbekacin were the most potent injectable antibacterial agents againstY. pestis. These results suggest that there are several new drugs, both oral and injectable, which exert excellent in vivo antibacterial activity against a mouse infection model and may be useful for the clinical treatment of plague.     

实验性精索静脉曲张对大鼠睾丸生精细胞凋亡的影响

目的 :探讨大鼠精索静脉曲张对睾丸生精细胞凋亡的影响 ,阐明精索静脉曲张引起不育的病理机制。　方法 :选用雄性SD大鼠 32只 ,随机分为假手术组、4 5d模型组、6 0d模型组及 90d模型组。采用肾静脉缩窄法建立精索静脉曲张动物模型 ,流式细胞术分别检测各组大鼠睾丸凋亡细胞数及各级生精细胞数。　结果 :假手术组未出现明显的凋亡峰 ,各模型组均出现明显的凋亡峰 ,且随着造模时间的延长凋亡峰增高。　结论 :精索静脉曲张可引起睾丸生精细胞大量凋亡 ,各级生精细胞数减少 ,这可能是精索静脉曲张引起睾丸生精功能障碍从而导致不育的根本机制     

Preventing heart disease: is treating the high risk sufficient?

Monte Carlo simulation was used to assess the effects of several intervention strategies on coronary heart disease mortality rates in a Finnish and a North American cohort. Lowering total serum cholesterol by 4%, smoking by 15%, and diastolic blood pressure by 3% for the whole cohort would be expected to reduce the incidence of non-fatal myocardial infarction by at least 13% and coronary heart disease deaths by at least 18%. Lowering serum cholesterol by 34%, diastolic blood pressure to 90 mmHg, and reducing smoking by 20% in the subset of the population with all three risk factors in the highest quartile would result in a 6-8% reduction in non-fatal myocardial infarction and a 2-9% reduction in deaths from coronary heart disease in these cohorts. These data demonstrate that in populations with a relatively high incidence of heart disease, treating the entire population will produce larger effects than focusing only on high-risk populations.     

Segregation analysis of leprosy in families of northern Thailand

Sixty-three families with multiple instances of leprosy were identified through a major leprosy treatment center in northern Thailand. Complex segregation analyses for single major genes or polygenic inheritance were performed using the maximum-likelihood routine POINTER to determine the most likely etiologic model of genetic susceptibility. Liability differences between men and women were considered in these models. When individuals were considered to be affected because they had any form of leprosy, a generalized major gene model with nearly dominant parameters on the liability scale, but additive penetrances, was found to be the most likely. When only those individuals who had tuberculoid forms of leprosy were considered to be affected, a recessive model was found to be the most likely; however, the discrimination between various models was poor. Further analyses are necessary to delineate genetic mechanisms to explain these apparently divergent results. In particular, methods of testing two locus models should be considered.