No abstract

It no longer seems likely that DNA molecules in situ have a uniform conformation, represented by the classical B-form helix. For example, recent structural studies have shown that in certain conditions DNA can have a left-handed (so-called Z-form) helix, and have revealed extensive sequence-dependent variations of B-DNA helical parameters. Such sequence-dependent variations in DNA structure can be investigated in solution with reagents that bind to DNA in a conformation-dependent manner, and cut one or both strands of the double-helix at the site of binding, as, for example, has been shown for the endonuclease DNase I3. We describe here a simple way to endow a DNA-binding ligand with the ability to cleave DNA--labelling with 125I. The radiochemical damage associated with 125I decay induces a double-stranded DNA break. Using this technique we have shown that a sequence of four consecutive A X T base pairs is a necessary, but not sufficient, condition for strong binding to DNA of the bis-benzamide Hoechst 33258--presumably the other important factor is the conformation of the double-helix at the site of the (A/T)4 sequence. We suggest 125I-Hoechst 33258 may be a useful new probe of DNA structure.

The construction industry poses a particular challenge for the making of occupational health and safety (OHS) risk control decisions which are equitable to all parties involved in the construction process. Typically, small business construction firms are engaged as subcontractors in the construction industry and are located at the lower end of the inter-organizational hierarchy in a construction project. As such, their ability to exert an influence on decision-making in the construction process is limited, despite their employees' day to day exposure to OHS risks. A qualitative study of understandings of OHS risk control was conducted among a sample of small businesses engaged in the Australian construction industry. Two OHS risks relevant to the construction industry were selected for study. One risk (falls from height) represented an immediate consequence while the other (occupational skin disease) represented a long-term health effect. Understandings of control for these OHS risks were explored during in-depth interviews. The results suggest that, at the small business end of the industry, there is a fatalistic resignation to OHS risks being an unavoidable part of the job. This leads to an emphasis on individual rather than technological controls for OHS risk. The implication of these findings for the effective management of OHS risk is discussed.Occupational Health And Safety Risk Control Small Business,

Risk and its control are important themes in occupational health and safety. In the current regulatory framework, risk is conceptualised as a probabilistic expression of hazard potential. However, social meanings of risk in the workplace may be different. The social context of work shapes the ways that risk is understood in the workplace, yet little research in occupational health and safety acknowledges it. A few studies of risk have used qualitative research methods to elicit understandings of risk at work; however, little research explores the experiences of both employers and employees. This study describes the narratives of risk in occupationai health and safety of employers and employees in the Victorian painting industry. Using ethnographic methods, we collected data about the contexts in which risk is experienced and the sources of risk that each group identifies. These narratives reveal that risk in the painting industry is constructed through the interactions of three factors: the social context, the hierarchical structure of the industry and the shared assumptions about risk control through individual skills and responsibilities. The narratives explain why occupational health and safety strategies focusing solely on individual behaviour change or technical measures will be unsuccessful.

Research information is often recommended as a solution for occupational disease and injury. This study asks whether publicly available research information on prevention of a well-documented occupational hazard is acted on by an important sector in industry. The hazard, allergic contact dermatitis (ACD) caused by epoxy resins in paints, is particularly significant for painters, who may have to leave their jobs as a consequence of the condition. No evidence is found, according to a priori criteria, that paint manufacturers/suppliers acted on known prevention measures for epoxy resin ACD that are within their control to implement. The findings suggest that availability of research information alone fails to solve health and safety problems. Recommendations for avenues of direct and indirect enforcement where voluntary implementation is absent in the painting industry are suggested.