STUDIES ON PROTEIN FOLDING,UNFOLDING AND FLUCTUATIONS BY COMPUTER SIMULATION III. Effect of Short-Range Interactions

The theoretical model of proteins on the two-dimensional square lattice, introduced previously, is extended to include the specific short-range interactions. Attractive long-range interactions with various specificities and non-specific repulsive long-range interactions in the form of self-avoidance of the polymer chain are also operative in the model. Dynamics of the model protein is studied by a Monte Carlo method. The short-range interactions are found to accelerate the folding and unfolding transitions. Non-specific part of the attractive long-range interactions have a competing effect of decelerating the transitions. When the short-range interactions are weighted beyond a certain extent over the attractive long-range interactions, the all-or-none character of the folding and unfolding transitions is destroyed. How the destruction proceeds is quantitatively expressed in terms of the S-H curves. The limiting case of dominance of the specific short-range interactions over the attractive long-range interactions is studied in detail. The lattice polymer in this limit does not behave like a globular protein at all. This observation leads to a reexamination of the currently popular notion of the dominance of the short-range interactions. A new concept of consistency is proposed to replace it. Possible mechanisms of the acceleration of the transitions by the specific short-range interactions are discussed.     

内皮素和一氧化氮的失平衡在哮喘发病中的作用

目的:探讨内皮素和一氧化氮的平衡在哮喘发病中的作用。方法:用卵白蛋白作为致敏原制备哮喘大鼠模型,建立大鼠离体气管环的张力测定并用内皮素-1(ET-1)作用观察张力的变化和JKC302及L-亚硝基精氨酸甲酯(L-NAME)对ET-1作用的影响。结果:ET-1对正常大鼠和哮喘大鼠离体气道均有强大的收缩作用,对哮喘组的作用明显高于正常对照组(P＜0.01)。在哮喘大鼠ET-1的收缩气道作用只能被ET_A拮抗剂JKC302部分阻断,比例为13.5%。L-NAME孵育哮喘大鼠气管环后,ET-1的气道收缩反应明显升高(P＜0.05)。结论:哮喘大鼠气道对ET-1的反应性明显提高,一氧化氮可影响ET-1的作用,在大鼠介导ET-1气道收缩作用主要是ET_B受体。气道ET-1和NO平衡失调是引起哮喘发生的机制之一。     

美国国家骨髓库20年回顾:成人无关供者造血干细胞移植

自1987年起,美国国家骨髓库(NMDP)提供了>30 000份URD-HCT,其中70%以上的受者是患有恶性血液病或获得性血液疾病的成人.在此期间发生很大变化,包括无偿捐献队伍的扩大、PBSCs采集、脐血库(UCB)的加入、HLA分型技术的进步、新药物的使用、低强度预处理(RIC)以及移植后免疫调节等.本文就过去20年NMDP成人受者HCT的数据及分析作一介绍.     

A huge low-grade fibromyxoid sarcoma of small bowel mesentery simulating hyper immune splenomegaly syndrome: a case report and review of literature

Introduction

Low-grade fibromyxoid sarcoma (LGFMS) is a rare non epithelial tumour. It usually arises from the smooth muscles of the extremities. It is, however, occasionally reported to arise from other regions of the body.

Case report

We report the case of a 32 year old man who complained of a progressive abdominal swelling of 4 months duration. There was associated abdominal discomfort and weight loss. Abdominal examination revealed a non-tender intra abdominal mass filling the abdomen completely. Abdominal ultrasound suggested a massive splenomegaly. Abdomina Computerized Tomography (CT) scan was not done due to financial constraints. At laparotomy, a large, pearl-coloured mass was found within the mesentery of the proximal jejunum, with dilated, tortuous vessels. It was resected along with the overlying 60cm of jejunum. It weighed 7.5kg. Histology and immunohistochemistry confirmed the diagnosis of lowgrade fibromyxoid sarcoma. Post-operative period was uneventful and there were no features of recurrent after 2 year of follow up.

Conclusion

LGFMS may cause a diagnostic dilemma, especially in a third world setting where preoperative diagnosis is hampered by lack of facilities and poverty. A high index of suspicion is needed for preoperative diagnosis, which is necessary for proper planning of the operation.     

Effects of evening light on body temperature

Abstract Six healthy male subjects aged 21–35 years participated in the present study. The subjects were exposed to dim light (150 lux) or bright light (3000 lux) at eye level, from 19.00 to 21.30 h for 5 days. Rectal temperature and wrist activity were monitored throughout the study period. Rectal temperature nadir was delayed significantly after the bright light exposure. Ease in sleep initiation and overall sleep quality, measured by questionnaire, were aggravated significantly by the evening bright light exposure. These results suggest that strong illumination at night may disturb nocturnal sleep.