Accumulation of streptococci on teeth in a laboratory microcosm (artificial mouth)

The accumulation on teeth of three strains of oral bacteria, ‘Streptococcus mitior’ LPA-1, Streptococcus mutans C67-1, and Streptococcus rattus BHT, was studied from 8 to 90 hours after inoculation. Direct and viable counts demonstrated that strains BHT and C67-1 accumulated more rapidly than strain LPA-1, with fastest growth during the first 16 hours (td8-16h 3.6-4.8 h). In older cultures, S. mutans and S. rattus continued to accumulate and a high proportion of the cells were viable. In contrast, ‘S. mitior’ cultures contained many non-viable organisms, possibly due to hydrogen peroxideinduced death. When S. rattus was co-cultured with ‘S. mitior’ it was strongly inhibited during the first 24 hours, but increased in proportion after 66 and 90 hours. It was concluded that in the interaction between ‘S. mitior’ and S. rattus during initial plaque development, a potentially rapid initial growth rate was of less importance than the ability to antagonise the other organism

Establishment of defined mixed bacterial plaques on teeth in a laboratory microcosm (artificial mouth)

Actinomyces viscosus WVU627, 'Streptococcus mitior' LPA-1 and Veillonella alcalescens OMZ193 were grown in pure or mixed culture on teeth in a model mouth which was supplied with synthetic saliva and an intermittent nutrient supplement containing 1% (w/v) glucose. All organisms became established in pure culture although V. alcalescens colonised very badly unless 1% (w/v) lactate was supplied in place of the glucose. Mixed cultures of all three organisms were readily established. In general, numbers and proportions of species varied widely in mixed culture, but were comparable to those observed in human dental plaque studies. When grown in association with A. viscosus and 'S. mitior', V. alcalescens achieved similar numbers to pure cultures supplied with lactate, thus demonstrating that a food chain existed. Higher viable counts of 'S. mitior' were obtained from mixed plaques, compared with pure cultures. However, less A. viscosus could be isolated when co-cultured with streptococci and veillonellae. Comparison of differential viable counts at 45 h, 66 h and 90 h after inoculation with these three organisms showed that both veillonellae and actinomyces increased in numbers and proportions with incubation time. Streptococcus mutans C67-1 became established when inoculated together with the other organisms, although it attained lower numbers compared with pure cultures. It appeared that S. mutans antagonised A. viscosus and partially displaced this organism in mixed plaques which contained all four species

JC and BK virus sequences are not detectable in leukaemic samples from children with common acute lymphoblastic leukaemia

Epidemiological evidence suggests that childhood leukaemia, and possibly common acute lymphoblastic leukaemia in particular, may have an infectious aetiology. Smith (1997 J Immunother20: 89–100) recently suggested that the critical infectious event occurs during pregnancy, and identified the polyoma virus JC as a candidate agent. In the present study we investigated whether genomes from the JC virus, and closely related BK virus, could be detected in leukaemic cells. No positive results were obtained suggesting that JC virus is unlikely to play a direct role in leukaemogenesis. © 1999 Cancer Research Campaig

can we call it a revolution women the labour market and european policy

In the USA the change in women's role in the economy over the last quarter-century has been likened to 'a quiet revolution'. Can we also talk of a quiet 'revolution' in Europe? The present article addresses this question by reviewing key developments in women's labour market position at EU level over the last 20 years. Full integration of women in the labour market was a focal point of European Employment Strategy, based on the understanding that it is an essential ingredient of gender equality; but it recently lost priority in favour of human rights and anti-discrimination goals. Policy responses to the financial crisis accelerated this change in priorities together with the perception that men are the real losers of the crisis. However, a stock-taking of women's integration into the labour market at EU level shows that two large obstacles stand in the way of full integration: regional imbalances and the secondary earner question. Female employment recently outperformed male employment, but fiscal consolidation policies currently hinder advancement in countries like the so-called GIPSI group, where progress is needed most. Meanwhile differences with respect to men in pension income or total earnings remain high at around forty percent. Reconciliation policy at EU level – leave design and care service provisioning in particular – had not consistently helped rebalance the gender division of labour within households. It needs recasting for a truly revolutionary change in women's role in the economy to materialize

Signals in the Soil: An Introduction to Wireless Underground Communications

In this chapter, wireless underground (UG) communications are introduced. A detailed overview of WUC is given. A comprehensive review of research challenges in WUC is presented. The evolution of underground wireless is also discussed. Moreover, different component of UG communications is wireless. The WUC system architecture is explained with a detailed discussion of the anatomy of an underground mote. The examples of UG wireless communication systems are explored. Furthermore, the differences of UG wireless and over-the-air wireless are debated. Different types of wireless underground channel (e.g., In-Soil, Soil-to-Air, and Air-to-Soil) are reported as well

Purchasing Involvement in Discontinuous Innovation: An Emerging Research Agenda

International audienceBuilding on a systematic review of the literature, we define and discuss why and how purchasing needs to be involved in the discontinuous innovation process. We argue that purchasing involvement in NPD should be considered mainly when the customer firm faces discontinuous innovation. Seeking to promote this emerging research agenda, we present three propositions to focus future studies and inspire practices: (a) technology sourcing and scanning out of the boundary of the supply base is an important stake to support discontinuous innovation as (b) to form an ambidextrous purchasing organization and (c) to develop absorptive capacity within purchasing function. The paper concludes by summarizing the conceptual implications of the paper, outlining some initial managerial recommendations