Thermodynamic stability of wild-type and mutant p53 core domain

Some 50% of human cancers are associated with mutations in the core domain of the tumor suppressor p53. Many mutations are thought just to destabilize the protein. To assess this and the possibility of rescue, we have set up a system to analyze the stability of the core domain and its mutants. The use of differential scanning calorimetry or spectroscopy to measure its melting temperature leads to irreversible denaturation and aggregation and so is useful as only a qualitative guide to stability. There are excellent two-state denaturation curves on the addition of urea that may be analyzed quantitatively. One Zn²⁺ ion remains tightly bound in the holo-form of p53 throughout the denaturation curve. The stability of wild type is 6.0 kcal (1 kcal = 4.18 kJ)/mol at 25°C and 9.8 kcal/mol at 10°C. The oncogenic mutants R175H, C242S, R248Q, R249S, and R273H are destabilized by 3.0, 2.9, 1.9, 1.9, and 0.4 kcal/mol, respectively. Under certain denaturing conditions, the wild-type domain forms an aggregate that is relatively highly fluorescent at 340 nm on excitation at 280 nm. The destabilized mutants give this fluorescence under milder denaturation conditions.     

WHO: reaching out to all

This article explains how the concept of health for all developed within the context of the history of the World Health Organization (WHO). By the early 1970s a new idea was taking shape in WHO. Medical services were failing to reach vast numbers. Health would have to emerge from the people themselves. In the heat of discussion the new strategy was clarified and given a name--primary health care (PHC). An ambitious target was set for it--no less than health for all by the year 2000. It was decided that the community itself had to be involved in planning and implementing its own health care. A new type of health worker was called for, chosen by the people from among themselves and responsible to the community but supported by the entire health system. In virtually all countries, the emphasis on curative care would have to be balanced by an equal emphasis on prevention. Almost 90% of WHO's Member States were prepared to share with one another detailed information about the problems facing their health systems. Industrial countries were beginning to realize that sophisticated medical technology was no guarantee of good health and that health for all through PHC offered an alternative. Millions of health workers have been trained, extending services to low-income groups that had no access to modern health care. Among health professionals, lack of understanding of the PHC concept and insufficient concern for social equity remain the principal constraints. Another problem is that expenditure on health care tends to be viewed as a drain on scarce resources rather than as an investment in the nation's future. The mommentum of health for all can be sustained only by governments implementing at home the policies they have collectively agreed on at The World Health Assembly in Geneva.     

Management of sphenoid sinus cerebrospinal fluid rhinorrhea: making use of an extended approach to the sphenoid sinus.

OBJECTIVES: Specific information addressing the management of cerebrospinal fluid (CSF) fistulas that originate from within the sphenoid sinus remains scant. The objective of this study was to review the cause and management of CSF rhinorrhea arising from the sphenoid sinus. STUDY DESIGN AND SETTING: This is a retrospective chart review of 12 cases of CSF rhinorrhea arising from the sphenoid sinus that occurred in 11 patients. All patients were treated at a single institution between 1994 and 1999. RESULTS: All patients were managed surgically with sphenoid sinus fat obliteration using an endoscopic sublabial, transseptal approach. This approach was successful for all 12 cases, with median duration of follow-up of 18 months. CONCLUSIONS: Endoscopically assisted transseptal repair of CSF fistulas that originate within the sphenoid sinus offers an alternate approach to previously described methods of repair in this region. Advantages include wide access to the entire sphenoid sinus, improved access to laterally pneumatized regions within the sphenoid sinus, and rostral mucosal closure over the repair within the sinus.     

The 2.0-Å resolution crystal structure of a trimeric antibody fragment with noncognate VH–VL domain pairs shows a rearrangement of VH CDR3

The 2.0-Å resolution x-ray crystal structure of a novel trimeric antibody fragment, a “triabody,” has been determined. The trimer is made up of polypeptides constructed in a manner identical to that previously described for some “diabodies”: a V_L domain directly fused to the C terminus of a V_H domain—i.e., without any linker sequence. The trimer has three Fv heads with the polypeptides arranged in a cyclic, head-to-tail fashion. For the particular structure reported here, the polypeptide was constructed with a V_H domain from one antibody fused to the V_L domain from an unrelated antibody giving rise to “combinatorial” Fvs upon formation of the trimer. The structure shows that the exchange of the V_L domain from antibody B1-8, a V_λ domain, with the V_L domain from antibody NQ11, a V_κ domain, leads to a dramatic conformational change in the V_H CDR3 loop of antibody B1-8. The magnitude of this change is similar to the largest of the conformational changes observed in antibody fragments in response to antigen binding. Combinatorial pairing of V_H and V_L domains constitutes a major component of antibody diversity. Conformationally flexible antigen-binding sites capable of adapting to the specific CDR3 loop context created upon V_H–V_L pairing may be employed by the immune system to maximize the structural diversity of the immune response.     

蒿甲醚引起小鼠体内日本血吸虫和曼氏血吸虫皮层变化

蒿甲醚引起小鼠体内日本血吸虫和曼氏血吸虫皮层变化１肖树华，沈炳贵，ＪａｃｋＨＯＲＮＥＲ２，ＢｒｉａｎＡＣＡＴＴＯ３（中国预防医学科学院寄生虫病研究所，世界卫生组织疟疾、血吸虫病和丝虫病合作中心，上海２０００２５，中国；２ＤｅｐａｒｔｍｅｎｔｏｆＣｌｉ...