When good Cdk5 turns bad

The cyclin-dependent kinase-5 (Cdk5) is critical to normal mammalian development and has been implicated in synaptic plasticity, learning, and memory in the adult brain. But Cdk-5 activity has also been linked to neurodegenerative diseases. Could a single protein have opposing effects? A new study shows that production of a neuronal protein capable of regulating Cdk-5 activity can turn Cdk-5 from "good" to "bad." The findings may have implications for the development and treatment of conditions like Alzheimer's disease.     

Cyclin-dependent kinase 5--a neuronal killer?

In dividing cells, cyclin-dependent kinases (Cdks) are cell cycle-associated protein kinases that regulate proliferation, differentiation, senescence, and apoptosis. In neurons that no longer divide, deregulation of Cdks, especially Cdk5, occurs in many neurological disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). Cdk5 is a unique member of the Cdk family because it does not play a critical role in cell cycle progression, and it is not activated by a cyclin. Instead, Cdk5 normally is activated by the regulatory protein p35. This Cdk5/p35 activity has emerged as an important regulator of proper development of the mammalian central nervous system. In vitro studies suggest that aberrant activation of Cdk5 by an endogenous truncated version (p25) of p35 might be a key event in the process of neurodegeneration. One enzyme responsible for cleavage of p35 to form p25 is calpain, a calcium-activated protease that has been shown to be involved in neuronal cell death. Recent studies provided important in vivo evidence that hyperactivation and redistribution of Cdk5 by p25 plays an essential role in the phosphorylation of "pathological" substrates (such as tau) and the cell death of neurons in experimental models of AD and PD. Because amyloid beta peptide, the primary neurotoxic component of amyloid plaques in AD, has been shown to increase the conversion of p35 to p25, aberrant activation of Cdk5 by p25 might be a pathway connecting amyloid beta toxicity to tau hyperphosphorylation in AD.     

A few points concerning the population growth of China's minority nationalities

How the populations of national minorities of China should develop in the future is a major problem that bears on the wealth and power of the homeland and the prosperity and development of the various nationalities themselves. The population of minority nationalities in China totaled only 35.52 million in 1953 and grew to 55.8 million in 1978. The speed of population growth of the different nationalities in different historical periods is closely related to the Party's policy and socioeconomic factors. Attention must be paid to the gap between population growth and the development of the economy, culture, education, health, and medical care as well as to other practical problems existing among the national minorities: 1) a young age structure, 2) early marriage and early reproduction are a widespread practice, 3) economic development still remains at a low level, and 4) cultural and educational level and health and medical care undertakings fall short of actual needs. Due to the serious imbalance between population growth and economic development, the lives of national minority peoples in most regions are still poverty-stricken. Implementing family planning programs among national minorities involves problems of understanding as well as many practical issues. The population growth of national minorities is a vital issue that calls for immediate, extensive, and in-depth research.     

A Note on Generalized Functional Linear Model and Its Application

Motivated by a biomarker study for colorectal neoplasia, we consider generalized functional linear models where the functional predictors are measured with errors at discrete design points. Assuming that the true functional predictor and the slope function are smooth, we investigate a two-step estimating procedure where both the true functional predictor and the slope function are estimated through spline smoothing. The operating characteristics of the proposed method are derived; the usefulness of the proposed method is illustrated by a simulation study as well as data analysis for the motivating colorectal neoplasia study.     

尹家沟帮子熏鸡:火车站里走出的宫廷美味

正春意暖暖,辽阔的黑土地孕育着无限生机。在锦州医巫闾山脚下,有一个美丽的小镇——沟帮子。每个来到这里的人,都会为一种味道而驻足,这个味道便是沟帮子熏鸡。沟帮子自清代以来就是辽西地区商贾云集之地。独特的地理优势繁衍着沟帮子人的勃勃商机。作为沟帮子熏鸡的突出代表,味出宫廷的尹家熏鸡便是借助     

一见惊艳刘羽琪

本期封面女孩,我们将为你介绍一个平凡的女孩。目前,19岁的她对你来说还很陌生,但是她的美,绝对能够吸引你的第一眼球。对,她就叫刘羽琪,一个美丽时尚的模特新星。不是每个女孩都喜欢安稳的生活,比如刘羽琪。在她看来,在不务正业的生活中寻求丰富多彩,才能体验规规矩矩的生活中所缺少的变化之美。     

论完整的人道主义

古罗马诗人特伦斯曾经说过这样一句话,“我是一个人,因此凡显示人性的东西,对我都不是陌生的”,这句话很可以成为我们称之为“文艺复兴时代的人”那种特殊历史现象的座右铭,而所谓“文艺复兴时代的人”,他不仅是“永恒的人”,而且还是能取得人类一切成就(包括艺术、科学、语言、文学、政治以至经济方面的成就)的人。经过漫长的“黑暗时代”(这样称呼它是带有一定的武断性和不恰当的)之后,到了欧洲文艺复兴时期,出现一种理想,一种全面发展人性的理想,它被称之为“人道主义”(这样