Influence of 0.5 ppm nitrogen dioxide exposure of mice on macrophage congregation in the lungs

Summary The lungs of 12 mice, half of which were exposed to continuous 0.5 ppm nitrogen dioxide for 3 weeks, were explanted in culture, and the instances of macrophage congregation were quantitated according to numbers of target cells involved, categories of congregation from three to 11 or more, numbers of macrophages participating in each category for the total cultures, and the influence of delaying explantation for 24 and 96 hr. A total of 9042 macrophages and 2140 epithelial and spindle target cells were counted in the outgrowths from 306 explants. The incidence of macrophage congregation (or numbers of target cells) was greater for the cultures from the NO₂-exposed animals, both with respect to total incidences between groups (p→0), and the 0-hr (p<0.001) and 24-hr (p<0.01) culture subgroups. In addition, the values for T₃ to T₆ macrophage congregation were individually and consistently greater for the exposed animal group. Postmortem interval stress at 96 hr appeared to result in large colonies, but they were reduced greatly in number. Also the incidence of macrophage congregation fell by 28% as compared to 0-hr and 24-hr subgroups. Supported by Grants NHLI No. HL 17412 and EPA No. R. 800881.     

Validatieonderzoek Welzijnsmeter-dementie

The Well-Being Measure – dementia is a digital observation instrument that assesses the well-being of persons with dementia on four domains of quality of life: Mental well-being, Physical well-being, Participation, and Living arrangements. Its goal is to assess the well-being of persons with dementia in an easy and positive way. Besides illness-related symptoms and problems, the instrument also assesses positive aspects of functioning. It visualizes the results and provides specific behavioural advice to the caregivers. The goal of the present article is to conduct a first psychometric analysis: factor structure, reliability (Cronbach’s alpha), concurrent, and convergent validity.Observations were carried out among 168 persons with dementia in eleven different small-scale psychogeriatric wards. Five existing instruments were used among 63 persons to validate the Well-Being Measure-dementia: quality of life, neuropsychiatric symptoms, care dependency, depression, and agitation.The expected factor structure was found in each of the four domains. Coefficients were high on the expected factor and low on the other factor(s). The scale means were on the positive side, but showed an adequate range and variability. Reliability was satisfactory to good. The relation with existing scales was moderate to strong. The pattern of relations was consistent with the measurement intentions of the different existing instruments.The Well-Being Measure – dementia appears to be a valid and reliable scale. Further studies should assess its test-retest reliability, sensitivity to change and relation with the course of dementia. Current experience shows that the instrument is also useful in everyday practice.     

Embodied Subjects and Fragmented Objects: Women’s Bodies,Assisted Reproduction Technologies and the Right to Self-Determination

This article focuses on the transformation of the female reproductive body with the use of assisted reproduction technologies under neo-liberal economic globalisation, wherein the ideology of trade without borders is central, as well as under liberal feminist ideals, wherein the right to self-determination is central. Two aspects of the body in western medicine—the fragmented body and the commodified body, and the integral relation between these two—are highlighted. This is done in order to analyse the implications of local and global transactions in women’s reproductive body parts for their right to self-determination and individual agency and what this means for their embodiment. We conclude by exploring whether women can become embodied subjects by exercising their proprietary right to their bodies through directing technology to achieve their own goals, while at the same time being fragmented into parts and losing their personhood and bodily integrity. This article has been translated and adapted from the Dutch version published in the Tijdschrift voor Humanistiek, 2006; 26(7).     

Trust transitivity in social networks

Non-centralized recommendation-based decision making is a central feature of several social and technological processes, such as market dynamics, peer-to-peer file-sharing and the web of trust of digital certification. We investigate the properties of trust propagation on networks, based on a simple metric of trust transitivity. We investigate analytically the percolation properties of trust transitivity in random networks with arbitrary in/out-degree distributions, and compare with numerical realizations. We find that the existence of a non-zero fraction of absolute trust (i.e. entirely confident trust) is a requirement for the viability of global trust propagation in large systems: The average pair-wise trust is marked by a discontinuous transition at a specific fraction of absolute trust, below which it vanishes. Furthermore, we perform an extensive analysis of the Pretty Good Privacy (PGP) web of trust, in view of the concepts introduced. We compare different scenarios of trust distribution: community- and authority-centered. We find that these scenarios lead to sharply different patterns of trust propagation, due to the segregation of authority hubs and densely-connected communities. While the authority-centered scenario is more efficient, and leads to higher average trust values, it favours weakly-connected "fringe" nodes, which are directly trusted by authorities. The community-centered scheme, on the other hand, favours nodes with intermediate in/out-degrees, in detriment of the authorities and its "fringe" peers.     

The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets

Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.