Apoptosis and Chemical Carcinogenesis

Long recognized as a normal component of organogenesis during development, apoptosis (programmed cell death) has recently been implicated in alterations of cell growth and differentiation. Tissue homeostasis is normally maintained by a balance between cell division and cell death, with apoptosis often functioning in complement to cell growth. Thus, antithetical parallels in chemical carcinogenesis can be drawn between apoptosis and the proliferative events more commonly addressed. While enhanced cell replication may contribute to an increased frequency of mutation, apoptosis within a tissue may counteract chemical carcinogenesis through loss of mutated cells. Many strong carcinogens act as tumor promoters, selectively expanding an initiated cell population advantageously over surrounding cells. Similarly, chemicals with a selective inhibition of apoptosis within an initiated population would offer a growth advantage. In contrast, chemicals causing selective apoptosis of initiated cells would be expected to have an anticarcinogenic effect. Selective apoptosis, in concert with cell-specific replication, may explain the unique promoting effects of different carcinogens such as the peroxisome-proliferating chemicals, phenobarbital, and 2,3,7,8-tetrachloro-dibenzo- p -dioxin (TCDD). Cell turnover, both cell growth and cell death, is central to the process of chemically induced carcinogenesis in animals and understanding its impact is a critical determinant of the relevance of chemically induced effects to man.     

Environmental impact statements

Environmental Impact Statements (EISs) present the results of a structured appraisal of the likely effects of a proposed development on the environment. Systematic methods of identification and assessment of potential effects of major projects have been developed in response to public concern about environmental quality. EISs were first introduced in the United States (US) in 1970 but they have since been adopted in a number of countries. In the United Kingdom (UK) EISs have been prepared for certain major projects, in particular for developments related to North Sea oil, but the procedure has not been formally introduced into the planning system. In this article the history of EIS in the US, UK and elsewhere is traced. Contents of EISs and methods of appraisal which may be included are described. Many attitudes towards EIS are based on the early years of EIS in the US where it was seen to be a slow, costly procedure frequently involving lengthy court battles. A review of EIS experience in the US shows that these problems have been exaggerated. Two major developers in the UK, BP and British Gas Corporation, consider EIS to be a valuable component of their project planning activities, ensuring that environmental aspects of developments are considered at an early stage. Finally some arguments for and against the formal introduction of EIS in the UK are examined. The article concludes that EIS will play an increasingly important role in the UK planning system.     

Systematic and chance components in fertility measurement

Abstract A Monte Carlo simulation model of fertility is developed to incorporate a decline in fecundability with age of women as well as a variation between women, and a family planning strategy in which couples prefer certain sizes of families and seek to lengthen the last planned birth interval. In the simulation of family planning and non-family planning populations, segmental parity tables are computed. These are tables in which the numbers of women in the columns representing the completed family sizes are sub-divided by rows representing the sizes of the families for shorter durations of marriage. The couples' success in their plans, under various conditions, and the rapidity with which family sizes stabilize, are among the results obtained from the simulation. The application of the tables to the estimation of family size preferences from observed family size distributions is also discussed.     

The importance of volitional narrative in treatment: An ethnographic case study in a work progran

The revised theory of the model of human occupation expands the concept of volition to include volitional narrative. This paper focuses on the application of this theory of volition to a client's experience in a work program. This ethnographic case study describes the volitional narrative and life world of one client who attended the occupational therapy work based program. For fifteen months the client was the subject of narrative interviews, participant observation, videotapes and telephone contacts. The findings will illustrate how knowledge of a client's volitional narrative and life world can shed critical light on understanding treatment conflicts. Finally, the discussion will underscore how important it is for work based programs to be designed to encourage therapists to adapt their treatment approaches to maximize the opportunities to seek out the client's volitional narratives and to create meaningful experiences that are consistent with the client's life world.     

Did the decline continue? Comparing the labor-market quality of United States immigrants from the late 1970s and late 1980s

The issue addressed in this paper is whether or not the decline in immigrant labor-market quality in the U.S. observed in the late 1960‘s and 1970‘s continued in the 1980‘s. Two other papers, Borjas (1995) and Funkhouser and Trejo (1995), have addressed the issue and have come up with contradictory results. In this paper I use a different data set, one that has advantages over the data sets used in the other studies. Given the rise in earnings inequality that has occurred in the United States over the 1980‘s, the returns to immigration for the more highly skilled will have increased relative to the low skilled, ceteris paribus. For this reason, it is possible that the skill decline of immigrants may have halted in the 1980‘s as immigrants of differing skill levels respond to the altered circumstances they would face in the United States. The empirical results show that the skill decline did indeed halt, a result which gives support to the Funkhouser/ Trejo result. Received July 24, 1995 / Accepted August 22, 1995