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Background: Active School Travel (AST) initiatives align with the Ottawa Charter for Health Promotion, which calls for 'creating supportive environments' and 'strengthening community action.' However, their reliance on volunteers poses sustainability challenges. The main objectives of this study were to document the motivations, satisfaction, and experiences of volunteers involved in sustaining two AST initiatives in Ontario for an entire school year., Methods: Two volunteer-led School Street initiatives in Kingston, Ontario successfully operated during pick-up and drop-off times of each school day. The first initiative operated for the entire 2021-2022 school year, and the second operated for the entire 2022-2023 school year. These initiatives were the first of their kind in the province of Ontario, Canada. Volunteers from both sites (n = 56) participated in online surveys and their motivations, satisfaction, and experiences of their role were compared using the 2-sided Fisher's Exact Test., Results: Over 80% of volunteers were highly motivated to promote safety and over 70% of volunteers were highly motivated to disrupt the status quo of unsupportive, car-centric urban environments by reimagining how streets can be used. By taking collective action to re-shape the environment around these public schools to support healthy, active living, our findings reveal that over 90% of volunteers were highly satisfied. Of the volunteers, 87% felt they contributed to child safety and 85% felt they had developed stronger community connections. They appreciated the short (i.e., 40 minute) time commitment of each shift, weekly email communications by the community organization leading the initiative, and the volunteer schedule. They also appreciated the positive social interactions during volunteer shifts, which they felt outweighed the minimal resistance they experienced., Conclusions: This research demonstrates the importance of logistical, motivational, and social factors in recruiting and retaining volunteers for community-led School Streets. Our findings support appealing to prospective volunteers' influence in achieving School Street objectives (e.g., improved safety) in recruitment efforts, as well as highlighting School Streets' innovative approach. Communicating with volunteers throughout School Street planning and implementation processes and limiting traffic in the closed street zone (i.e., by excluding the school staff parking lot and private driveways from the scope) are additional recommendations based on the findings of this study., (© 2024. The Author(s).)

Background: Active transportation (AT) and free play (FP) are the primary ways in which children engage in unstructured physical activity in cities, with independent mobility (IM) gaining increased attention as a potential precursor of AT and FP. However, current trends show that children are engaging in less FP and AT, and have less IM, than previous generations and it is not well understood how these practices, and their interrelatedness, differ by neighbourhood-level socio-economic stats (SES) and municipal contexts., Objectives: This study aims to address the gaps in knowledge by quantifying, comparing, and correlating IM, AT, and FP practices in high and low-SES neighbourhoods within and across the cities of Montreal and Kingston, Canada., Methods: 584 questionnaires were distributed among children in grades 1 to 5, living in low- and high-SES neighbourhoods of these two citiesResultsEngagement in the three practices was low in every study neighbourhood, though all three practices were higher in high-SES compared to low-SES neighbourhoods in both cities. Levels of FP were higher in Kingston compared to Montreal, while AT was higher in Montreal than in Kingston., Conclusion: This study revealed social inequalities in all three of these practices based on socioeconomic status and city. Since IM is likely a precursor to both independent FP and AT, more research is warranted into how our cities can become more conducive to IM in children, particularly in low SES neighbourhoods where children have less freedom of movement independently and otherwise., Competing Interests: The authors declare that they have no known competing financial interests, and three of the four authors have no personal relationships, that could have appeared to influence the work reported in this paper. One of the authors (PC) resides in one of the high SES Kingston neighbourhoods that was selected for this study, and knows some of the survey respondents from this neighbourhood personally., (© 2024 The Authors.)

Automobile-centric community design, or 'motornormativity', severely restricts opportunities for children to engage in active transportation (AT) and outdoor free play (OFP). As these activities are critical to children's health and well-being, their decline has become a major public health concern. Meanwhile, independent mobility (IM) has emerged as a critical determinant of child development and well-being. Defined as 'the freedom for children to move about their neighbourhood without adult supervision', children's IM is in direct conflict with motornormativity. And yet, very few studies explore these three practices together, and very few public health interventions actively confront motornormativity to support children's IM. We hypothesise that IM is foundational to AT and OFP, and that efforts to increase AT and OFP are doomed to fail without a deep understanding of the barriers to children's IM. We conclude with ideas to study and support children's IM in public health research and practice., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: The authors declare that they do not have any conflicts of interest.

This study was conducted to determine whether T cell populations are responsible for modulating placental development during gestation in cattle. It was hypothesized that CD4+CD25+ and γ/δ+ T cells modulate gene expression, based on mRNA transcript abundances, and promote proliferation and survival of trophoblast cells. Peripheral blood was collected from cows at 160 to 180 days of gestation and non-pregnant cows, T cell populations CD8+, CD4+, CD4+CD25+, CD24+CD25-, and γ/δ+ T cells were isolated, cultured for 48 h, and supernatant was collected. Placental samples were digested, and trophoblast cells were cultured for 24 h. Trophoblast cells were cultured with 50 μL of T cell-conditioned media and 50 μL of fresh culture media for an additional 48 h. Samples in control wells were treated with unconditioned media. Trophoblast cell proliferation, apoptosis, and mRNA transcript assays were conducted. There was no effect of T cell population on trophoblast apoptosis rate, proliferation, and relative mRNA transcript abundances. The T cell supernatant from pregnant and non-pregnant cows induced greater apoptosis rates in trophoblast cells than unconditioned media. Trophoblast cells proliferated less when treated with T cell supernatant from pregnant compared to unconditioned medium and non-pregnant cows. Treatment with the T cell supernatant from pregnant cows resulted in larger abundances of BMP5, IGF1R, PAG10, FGF2, RSPO3 and TMED2 and also a lesser abundance of FGF2 mRNA transcript than non-pregnant group and unconditioned media treatments. Supernatant from T cell derived from pregnant cows modulates trophoblast mRNA transcript abundances differently from T cell supernatant of non-pregnant cows., (Published by Elsevier B.V.)

Criminologists and correctional administrators are continuously interested in understanding criminal career trajectories, including desistance, particularly to further develop correctional programming. One program that seeks to promote successful reentry by triggering desistance for youth and adults is the IF Project, founded in 2008 in Washington State. A central component of the IF Project program requires participants to write narratives that ask them to reflect on their journey to crime and to think about what they would have needed to break away from their criminal career trajectory. This research reports on a content analysis of 171 of these writings by adult prisoners in Washington State. Results from the content analysis reveal distinct and overlapping themes for both men and women that highlight the identity change process. Research and policy implications are discussed.

Background: Numerous cross-sectional studies have consistently demonstrated an association between attributes of urban form or 'walkability' and individual- and population-level physical activity (PA) patterns. However, in the absence of longitudinal research, the self-selection problem undermines the claim that a walkable built form produces more physically active people. Through a longitudinal pilot study of 'imminent movers' in Ontario using a quasi-experimental approach, we sought to examine the feasibility of longitudinal methods that would produce stronger evidence for a causal relationship between the built environment and PA levels., Methods: Participants were recruited using publicly available real estate listings. Successful recruits were sent a PA diary to track their activity for a week, and were also scheduled for a 45-min phone interview that collected demographic details, neighbourhood perceptions and self-efficacy for walking, and verified the PA diary. Following their move, participants were given the same tasks and then sorted into groups based on changes in their neighbourhood walkability (measured with Walk Score) from baseline to follow-up., Results: There were challenges in recruiting a sufficient number of participants and counter-factuals to examine the relationship between changes in walkability and PA. Our limited sample showed a substantial decrease in Walk Score over the entire sample, from an average of 45.8 to 30.6, with most participants moving to less walkable areas. From baseline to follow-up, the largest declines in reported self-efficacy for walking were to grocery stores, banks, and for entertainment. For the entire sample, utilitarian PA decreased, while recreational and job-related PA increased., Conclusions: This pilot study highlighted the methodological challenges involved in collecting quasi-experimental evidence on the effect of walkable environments on PA. Additionally, the low sample size and the tendency for most participants to move to less walkable areas meant there were insufficient counter-factuals for study of the effect of walkability on PA. Despite these challenges, we saw important changes in self-efficacy for walking that were commensurate with changes to the built environment. In sum, while longitudinal research on health and the built environment is urgently needed, recruiting an adequate sample size for a quasi-experimental study such as this is extremely challenging.

The gastric armature of decapod foregut is a feeding structure that sparks controversial debates about the role dietary and historical components have in shaping its morphological traits. Having previous information about the natural diet is an interesting way to gather evidence on this issue. For the present study, we analyzed the morphological traits of gastric ossicles involved directly in the maceration of food in nine species of freshwater crabs of the family Trichodactylidae (Brachyura: Decapoda) representing five genera, three tribes and two subfamilies. The analyzed gastric ossicles were quite consistent among closely related species, suggesting that the observed traits had a clear phylogenetic component. However, it was also noted that the morphological traits of the gastric teeth of trichodactylid crabs match well with the natural diet and presented likeness with general features of other species with a similar trophic habit. We discuss the influence of phylogeny and function on the design of morphological traits and propose to quantify the role of phylogeny and function in shaping morphological traits through the analysis of phylogenetic signals., Competing Interests: The authors declare there are no competing interests.

Crustaceans exhibit great diversity of feeding structures with morphological traits that are useful to infer the general trophic habits of species. In this study, we analyzed the functional morphology of comminuting feeding structures (mandibles, chelipeds, gastric mill) of the freshwater crab Trichodactylus borellianus directly related with the food fragmentation. The heterochely and mechanical advantage (MA) of the chelae were also studied. In both analyses, we considered the relationship between morphology and the natural diet. We expected to find a consistent relation between feeding habits and morphological traits. In general, we found simple structures armed with uniform setal systems and feeding appendages without pronounced teeth or spines. Mandibles have primarily cutting functions, helping with the food anchoring and fragmentation with mandibular palps armed with pappose setae. Chelipeds were covered with spines and simple setae. Adult males exhibited right-handedness with high MA of the major chelae. The ingested, relatively large pieces of food are finally chewed by a gastric mill equipped with sharp cusps characteristic of decapods with low ingestion of crude fiber material. The morphology of the feeding apparatus revealed that it is well adapted to an omnivorous diet, being able to cope with dietary changes., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: Household food insecurity (HFI) affects approximately 13% of Canadian households and is especially prevalent among low-income households. Actions to address HFI have been occurring primarily at the local level, despite calls for greater income supports from senior governments to reduce poverty. News media may be reinforcing this trend, by emphasizing food-based solutions to HFI and the municipal level as the site where action needs to take place. The objective of this study was to examine the level and framing of print news media coverage of HFI action in Canada., Methods: Using a quantitative newspaper content analysis approach, we analyzed 547 articles gathered from 2 national and 16 local/regional English-language newspapers published between January 2007 and December 2012., Results: News coverage increased over time, and over half was produced from Ontario (33%) and British Columbia (22%) combined. Of the 374 articles that profiled a specific action, community gardens/urban agriculture was most commonly profiled (17%), followed by food banks/meal programs (13%); 70% of articles implicated governments to take action on HFI, and of these, 43% implicated municipal governments. Article tone was notably more negative when senior governments were profiled and more neutral and positive when municipal governments were profiled., Conclusion: News media reporting of this issue in Canada may be placing pressure on municipalities to engage in food-based actions to address HFI. A more systematic approach to HFI action in Canada will require more balanced media reporting that acknowledges the limitations of food-based solutions to the income-based problem of HFI.

The concept of 'health literacy' refers to the personal and relational factors that affect a person's ability to acquire, understand and use information about health and health services. For many years, efforts in the development of the concept of health literacy exceeded the development of measurement tools and interventions. Furthermore, the discourse about and development of health literacy in public health and in clinical settings were often substantially different. This paper provides an update about recently developed approaches to measurement that assess health literacy strengths and limitations of individuals and of groups across multiple aspects of health literacy. This advancement in measurement now allows diagnostic and problem-solving approaches to developing responses to identified strengths and limitations. In this paper, we consider how such an approach can be applied across the diverse range of settings in which health literacy has been applied. In particular, we consider some approaches to applying health literacy in the daily practice of health-service providers in many settings, and how new insights and tools--including approaches based on an understanding of diversity of health literacy needs in a target community--can contribute to improvements in practice. Finally, we present a model that attempts to integrate the concept of health literacy with concepts that are often considered to overlap with it. With careful consideration of the distinctions between prevailing concepts, health literacy can be used to complement many fields from individual patient care to community-level development, and from improving compliance to empowering individuals and communities., (Copyright © 2016. Published by Elsevier Ltd.)

Public transit ridership offers valuable opportunities for modest amounts of daily physical activity (PA). Transit is a more feasible option for most Canadian commuters who live too far from work to walk or cycle, yet public transit usage in midsized Canadian cities has historically remained low due to inefficient transit service. The objectives of this longitudinal study were threefold: to assess whether the introduction of express transit service in the low-density city of Kingston, Ontario, has translated to greater transit use among a targeted employee group; to document the characteristics of those employees that have shifted to transit; and to examine the PA levels of employees using transit compared to other commute modes. An online survey was administered in October 2013 and October 2014 to all non-student employees at Queen's University. 1356 employees completed the survey in 2013, and 1123 in 2014; 656 of these employees completed the survey both years, constituting our longitudinal sample. Year-round transit ridership increased from 5.5% in 2013 to 8.5% in 2014 (p < 0.001). Employees who shifted to transit had fewer household-level opportunities to drive to work and more positive attitudes toward transit. Transit commuters accrued an average of 80 minutes/week of commute-related PA, and 50 minutes/week more total PA than those that commuted entirely passively. Kingston Transit's express service has stimulated an increase in transit ridership among one of their target employers, Queen's University. The findings from this study suggest that shifting to transit from entirely passive commuting can generate higher overall PA levels.

Background: Individuals that engage in active transportation (AT) have healthier weights and fitness levels. Most AT research has focused on work- or school-based destinations. Meanwhile, little is known about the differences between individuals that engage in the most common forms of AT--walking and cycling--and how these AT patterns vary by destination, duration, and season., Methods: We recruited 1400 randomly sampled adults (350 per season) in Kingston, Ontario, Canada to complete a cross-sectional telephone survey. The survey captured the prevalence, destinations, and duration of AT, and we examined the observed differences by mode., Results: The majority (72%) of respondents were AT-users; walking constituted 93% of overall mode share. Cyclists were more likely to be male, younger, and employed than walkers. Walkers tended to access neighborhood-based destinations, while cyclists were more likely to use AT to get to work. AT duration was comparable by mode, ranging from approximately 8 to 20 minutes. Overall rates of AT were lowest in the winter, but walking rates were reasonably high year-round., Conclusions: Beyond commuting to work and school, policy-makers and planners should consider the breadth of destinations accessed by different modes when aiming to increase physical activity through AT in their communities.

The proliferation of gambling opportunities in Canada, coupled with an aging population, has led to an increased prevalence of gambling among older adults. Encouraged by this trend, gambling industries have modified their activities to attract and market to this group. Yet, older adults are not a homogeneous group. The life experiences, values, and attitudes shared by generations make a cohort-specific analysis of gambling among older adults a worthwhile pursuit. Drawing from the Dualistic Model of Passion (Vallerand et al. in J Pers Soc Psychol 85(4):756-767, 2003), we discuss the role of passion in shaping gambling behaviours, and the implications of a harmonious or obsessive passion on the benefits and risks to two distinct generations of older adults. Based on their generational attributes, we posit that members of the Silent Generation (those born between 1925 and 1942) stand to gain more from the benefits of recreational gambling, but also stand lose more from problem gambling, than their children's generation, the Baby Boomers (those born between 1942 and 1964). Preventative strategies to assist problem gambling seniors, along with recommendations for further research, are discussed.

Food insecurity is an urgent public health problem in Canada, affecting 4 million Canadians in 2012, including 1.15 million children, and associated with significant health concerns. With little political will to address this significant policy issue, it has been suggested that perhaps it is time for Canada to try a food stamp-style program. Such a program could reduce rates of food insecurity and improve the nutritional health of low-income Canadians. In this article, we explore the history of the US food stamp program; the key impetus of which was to support farmers and agricultural interests, not to look after the needs of people living in poverty. Though the US program has moved away from its roots, its history has had a lasting legacy, cementing an understanding of the problem as one of lack of food, not lack of income. While the contemporary food stamp program, now called Supplemental Nutrition Assistance Program (SNAP), reduces rates of poverty and food insecurity, food insecurity rates in the USA are significantly higher than those in Canada, suggesting a food stamp-style program per se will not eliminate the problem of food insecurity. Moreover, a food stamp-style program is inherently paternalistic and would create harm by reducing the autonomy of participants and generating stigma, which in itself has adverse health effects. Consequently, it is ethically problematic for health promoters to advocate for such a program, even if it could improve diet quality., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The experiences of settlement in a new country (e.g., securing housing and employment, language barriers) pose numerous challenges for recent immigrants that can impede their health and well-being. Lack of social support upon arrival and during settlement may help to explain why immigrant mental health status declines over time. While most urban centers in Canada offer some settlement services, little is known about how the availability of social supports, and the health statuses of recent immigrants, varies by city size. The objective of this mixed-methods study was to examine the relationship between self-perceived mental health (SPMH), social support availability, and urban center size, for recent immigrants to Canada. The quantitative component involved analysis of 2009-2010 Canadian Community Health Survey data, selecting for only recent immigrants and for those living in either large or small urban centers. The qualitative component involved in-depth interviews with managers of settlement service organizations located in three large and three small urban centers in Canada. The quantitative analysis revealed that social support availability is positively associated with higher SPMH status, and is higher in small urban centers. In support of these findings, our interviews revealed that settlement service organizations operating in small urban centers offer more intensive social supports; interviewees attributed this difference to personal relationships in small cities, and the ease with which they can connect to other agencies to provide clients with necessary supports. Logistic regression analysis revealed, however, that recent immigrants in small urban centers are twice as likely to report low SPMH compared to those living in large urban centers. Thus, while the scope and nature of settlements services appears to vary by city size in Canada, more research is needed to understand what effect settlement services have on the health status of recent immigrants to Canada, especially in smaller urban centers., (Copyright © 2015. Published by Elsevier Ltd.)

Measures of hydrologic connectivity have been used extensively to describe spatial connections in riverine landscapes. Hydrologic fluctuations constitute an important macrofactor that regulates other environmental variables and can explain the distribution and abundance of organisms. We analysed morphological variations among individuals of two freshwater crab species, Zilchiopsiscollastinensis and Trichodactylusborellianus, from localities of the middle Paraná River basin during two phases of the local hydrological regime. Specimens were sampled at sites (localities) of Paraná River, Saladillo Stream, Salado River and Coronda River when water levels were falling and rising. The conductivity, pH, temperature and geographical coordinates were recorded at each site. The dorsal cephalothorax of each crab was represented using 16 landmarks for Zilchiopsiscollastinensis and 14 landmarks for Trichodactylusborellianus. The Canonical Variate Analyses showed differences in shape (for both species) among the crabs collected from the Paraná and Salado Rivers during the two hydrologic phases. We did not find a general distribution pattern for shape among the crab localities. During falling water, the shapes of Zilchiopsiscollastinensis were not related to latitude-longitude gradient (i.e., showing greater overlap in shape), while during rising water the shapes were ordered along a distributional gradient according to geographical location. Contrary, shapes of Trichodactylusborellianus were related to latitude-longitude during falling water and were not related to distributional gradient during rising water. The cephalothorax shape showed, in general, no statistically significant covariations with environmental variables for either species. These results show that each freshwater crab species, from different localities of the middle Paraná River, remain connected; however, these connections change throughout the hydrologic regime of the floodplain system. This study was useful for delineating how the relation among shapes of crabs of localities varies during two phases of the hydrological regime and for estimating the connections and geographical patterns in the floodplain system.

Household food insecurity (HFI) is a persistent public health problem affecting 3.8 million Canadians. While the causes of HFI are rooted in income insecurity, solutions to HFI have been primarily food-based, with the bulk of activity occurring at the municipal level across Canada. We conceptualize these municipal-level actions as falling within three models: "charitable", "household improvements and supports" and "community food systems". Many initiatives, especially non-charitable ones, generate widespread support, as they aim to increase participants' food security using an empowering and dignified approach. While these initiatives may offer some benefits to their participants, preliminary research suggests that any food-based solution to an income-based problem will have limited reach to food-insecure households and limited impact on participants' experience of HFI. We suspect that widespread support for the local-level food-based approach to HFI has impeded critical judgement of the true potential of these activities to reduce HFI. As these initiatives grow in number across Canada, we are in urgent need of comprehensive and comparative research to evaluate their impact on HFI and to ensure that municipal-level action on HFI is evidence-based.

Canada is the only country in the world to offer universal comprehensive public health insurance that excludes outpatient prescription medicines. Few scholars have attempted to explain this policy puzzle. We study media coverage of prescription drug financing from 1990 to 2010 to elucidate how the policy problem and potential solutions have been framed in media discourse and identify the actors that have dominated media texts. We confirm previous analyses that have revealed the significant role played by policy elites in media coverage of health reform debates. We also find that proposed expansions to public coverage are presented as a financial liability that could "crowd out" the existing (and popular) public insurance program. Within the context of a predominantly public funded system, framing of incremental expansion reorients away from values and toward discourse related to costs--both of the current system and of potential reforms. This may reflect a strategic narrative used by actors to maintain "silos of values" for coverage for prescription medicines versus those for other services. This has significant implications for the motivation for reform among the electorate and politicians alike, and for the extent to which policy developments, if they occurred, would legitimately reflect societal values for health financing.

Background: Unlike traditional primary care centres, part of the Community Health Centre (CHC) mandate is to address upstream health determinants. In Ontario, CHCs refer to these activities as Community Initiatives (CIs); yet, little is known about how CIs operate. The objective of this study was to examine the scope, resource requirements, partnerships, successes and challenges among selected Ontario CIs., Methods: We conducted qualitative interviews with 10 CHC staff members representing 11 CIs across Ontario. CIs were identified through an online inventory, recruited by e-mail and interviewed between March and June 2011., Results: Most CIs aim to increase community participation, while addressing social isolation and poverty. They draw minimal financial resources from their CHC, and employ highly skilled staff to support implementation. Most enlist support from various partners, and use numerous methods for community engagement. Successes include improved community relations, increased opportunities for education and employment and rewarding partnerships, while insufficient funding was a commonly identified challenge., Conclusions: Despite minimal attention from researchers and funders, our findings suggest that CIs play key capacity-building roles in vulnerable communities across Ontario, and warrant further investigation., (Copyright © 2014 Longwoods Publishing.)

Objectives: Canada is an increasingly urban nation, with considerable health inequities (HI) within its urban centres. While Canadian municipalities have a range of policy and planning levers that could reduce the burden of HI, little is known about how municipal employees perceive the capacities of municipal governments to address HI within their jurisdictions. This study sought to capture these perceptions through a survey of politicians and senior-level staff working in Metro Vancouver municipalities., Methods: The survey was administered by mail to 637 politicians and senior-level staff from 17 municipal governments in Metro Vancouver. The survey captured respondents' perceptions on the responsibilities of, opportunities for, and constraints on, municipal-level action to address HI, as well as respondents' input on existing municipal policies and programs that could reduce HI in their jurisdictions., Results: Respondents perceived senior governments to bear greater responsibility for reducing HI than municipalities. Investing in "parks & recreation facilities" was considered the most promising policy lever for addressing HI, while "insufficient federal and provincial funding" was perceived to be the greatest constraint on municipal action. "Affordable housing" and "recreational programs" were the most commonly identified existing strategies to address HI in the municipalities sampled., Conclusions: Our findings revealed concerns about inter-governmental downloading of responsibilities, and behaviour-based assumptions of disease etiology. To advance an urban health equity agenda, more work is needed to engage and educate municipal actors from a range of departments on the social determinants of health inequities.

The efficiency of solvent based extraction methods used to remove explosive residues from four different swab types was investigated. Known amounts of organic and inorganic residues were spiked onto a swab surface with acetonitrile or ethanol:water combined with ultrasonication or physical manipulation used to extract the residues from each swab. The efficiency of each procedure was then calculated using liquid chromatography-ultraviolet detection for organic residues and ion chromatography for inorganic residues. Results indicated that acetonitrile combined with physical agitation proved to be the most efficient method; returning analyte recoveries c. 95% for both alcohol based swabs and cotton balls. Inorganic residues were efficiently extracted using ethanol:water, while the use of acetonitrile followed by water significantly reduced the recovery of inorganic residues. Swab storage conditions were then investigated with results indicating decreased storage temperatures are required to retain the more volatile explosives., (© 2013 American Academy of Forensic Sciences.)

The use of an organic solvent to extract explosive residues from hand swabs and postblast debris inevitably leads to the coextraction of unwanted materials, usually in far greater quantities than any explosive residue. In this study, the extraction efficiency of a number of solvent cleanup procedures including solid-phase extraction (SPE), adsorbent resins such as Chromosorb-104, and traditional materials such as silica and Florisil was calculated using a quantitative liquid chromatography-ultraviolet (LC-UV) detection procedure. The Oasis(®) HLB cartridge outperformed other cleanup procedures, with analyte recoveries approaching 95%, while the Amberlite XAD-7 procedure returned the lowest overall recoveries. The matrix rejection ability of each method was then determined using a simulated highly contaminated matrix, with the adsorbent resins showing a higher degree of matrix rejection, which is seen as a reduction in background noise in the UV chromatogram using 210 nm detection., (© 2012 American Academy of Forensic Sciences.)

AL cardiomyopathy leading to heart failure (HF) represents a significant cause of morbidity and mortality in systemic amyloidosis. However, the paucity of robust in vivo models of AL-induced cardiac dysfunction has limited our ability to probe the mechanisms of AL heart disease. To address this problem, we have developed a model of AL HF in zebrafish embryos by injection of in vitro transcribed mRNA encoding amyloidogenic light chain (aLC) into fertilized oocytes. We demonstrate that expression of aLC causes cardiomyopathy in developing zebrafish without significantly impairing extracardiac development. The cardiac ventricle of embryos expressing aLC exhibit impaired contractility, smaller size, and increased myocardial thickness which result in congestion and edema, features paralleling the clinical manifestations of amyloid cardiomyopathy. Phosphorylated p38, a marker of oxidative stress, was increased in response to aLC expression. No evidence of amyloid fibril deposition was identified. Thus, expression of aLC mRNA in zebrafish results in cardio toxic effects without fibril deposition. This is consistent with prior evidence indicating that aLC oligomers mediate cardiac dysfunction in vitro. This model will allow exploration of amyloid pathophysiology and testing of interventions to reduce and reverse the deleterious effects of amyloidosis on myocardial function.

In an effort to improve patient safety and health care outcomes, continuing medical education has begun to focus on performance improvement initiatives for physician practices. Boston University School of Medicine's (BUSM) Continuing Nursing Education Accredited Provider Unit has begun a creative project to award nursing contact hours for nurses' participation in performance improvement activities. This column highlights its initial efforts., (Copyright 2012, SLACK Incorporated.)

Cities are important sites for intervention on social determinants of health (SDOH); yet, little is known about how influential local actors, namely workers in municipal governments (GOVs) and community-based organizations (CBOs), perceive the SDOH. Capturing and comparing perceptions between these groups are important for assessing how SDOH discourse has permeated local actors' thinking--a meaningful endeavour as local-level health equity action often invokes inter-institutional partnerships. This paper compares SDOH perceptions between CBO workers in Hamilton, Ontario, with politicians and senior-level staff in GOVs in Vancouver, British Columbia, based on two studies with surveys containing identical questions on SDOH perceptions. Overall, there was high comparability between the groups in their relative ratings of the SDOH. Both groups assigned high levels of 'influence' and 'priority' to 'healthy lifestyles' and 'clean air and water' and lower levels to 'strong community' and 'income'. Given the importance of a shared vision in collaborative enterprises, the comparability of perceptions between the groups found here holds promise for the prospect of inter-institutional partnerships. However, the low rating assigned to more structural health determinants suggests that more work is needed from researchers and advocates to effectively advance a health equity agenda at the local level in Canada.

Freshwater decapod crustaceans are important components of food webs in these environments, but little is known about the diet of species that live in tropical waters. We studied the feeding ecology of the prawn Pseudopalaemon bouvieri and its population structure in two different areas with six lagoons, with a different composition and abundance of aquatic macrophytes. At each site of macrophytes banks, 18 prawns sample was collected with a hand net (1mm mesh size) from 1m2. In the laboratory, prawns cephalothorax length was measured, sex determined, and a total of 208 stomachs were examined for food items. Our results showed that the population abundance varied between 10 ind/m2 and 1 411 ind/m2. The cephalothorax length ranged between 6mm and 21mm, and the male:female ratio varied between 0.3 and 1.0, with a higher proportion of ovigerous females (21%) in area one than area two. P. bouvieri is omnivorous, and its diet was principally based on algae, plant remains, Protozoa, Rotifera, Oligochaeta, Crustacea, Insecta, detritus and other items. The analysis of the stomach content did not reveal any significant difference in the diet between juveniles and adults, and males and females of both areas consumed a similar diet (Kruskal-Wallis test p=0.8273). We concluded that the dietary items consumed by prawns and the niche breadth were similar between the two areas, although the proportion of items consumed varied between lagoons of both areas. The density of P. bouvieri was different between areas, but the size of cephalothorax (CL) was similar.

Background: The 1986 Ottawa Charter for Health Promotion coincided with a preponderance of research, worldwide, on the social determinants of health and health inequities. Despite the establishment of a 'health inequities knowledge base', the precise roles for municipal governments in reducing health inequities at the local level remain poorly defined. The objective of this study was to monitor thematic trends in this knowledge base over time, and to track scholarly prescriptions for municipal government intervention on local health inequities., Methods: Using meta-narrative mapping, four bodies of scholarly literature - 'health promotion', 'Healthy Cities', 'population health' and 'urban health' - that have made substantial contributions to the health inequities knowledge base were analyzed over the 1986-2006 timeframe. Article abstracts were retrieved from the four literature bodies using three electronic databases (PubMed, Sociological Abstracts, Web of Science), and coded for bibliographic characteristics, article themes and determinants of health profiles, and prescriptions for municipal government interventions on health inequities., Results: 1004 journal abstracts pertaining to health inequities were analyzed. The overall quantity of abstracts increased considerably over the 20 year timeframe, and emerged primarily from the 'health promotion' and 'population health' literatures. 'Healthy lifestyles' and 'healthcare' were the most commonly emphasized themes in the abstracts. Only 17% of the abstracts articulated prescriptions for municipal government interventions on local health inequities. Such interventions included public health campaigns, partnering with other governments and non-governmental organizations for health interventions, and delivering effectively on existing responsibilities to improve health outcomes and reduce inequities. Abstracts originating from Europe, and from the 'Healthy Cities' and 'urban health' literatures, were most vocal regarding potential avenues for municipal government involvement on health inequities., Conclusions: This study has demonstrated a pervasiveness of 'behavioural' and 'biomedical' perspectives, and a lack of consideration afforded to the roles and responsibilities of municipal governments, among the health inequities scholarly community. Thus, despite considerable research activity over the past two decades, the 'health inequities knowledge base' inadequately reflects the complex aetiology of, and solutions to, population health inequities.

Background: Clinicians have been slow to embrace support for patient self-management., Objective: To explore clinicians' beliefs about patient self-management and specifically assess which patient competencies clinicians believe are most important for their patients., Methods: Using items adapted from the Patient Activation Measure (PAM) as a basis, a new measure that assesses clinicians' beliefs about patient self-management was created using Rasch analysis. The development and testing of the new measure Clinician Support for Patient Activation Measure (CS-PAM) is described here. Primary care clinicians from the UK and the USA were recruited to participate in the survey (n = 175)., Findings: The CS-PAM reliably measures clinician attitudes about the patient role in the care process. Clinicians strongly endorse that patients should follow medical advice but are less likely to endorse that patients should be able to make independent judgements or take independent actions. Endorsed to a lesser degree was the idea that patients should be able to function as a member of the care team. Least endorsed was the notion that patients should be independent information seekers., Discussion: Clinicians' views appear to be out of step with current policy directions and professional codes. Clinicians need support to transition to understand the need to support patients as independent actors.

We investigated the relationship between perceptions of neighbourhood quality and self-rated health for residents of eight suburban neighbourhoods with modestly contrasting income profiles in the Vancouver Census Metropolitan Area. Survey respondents from lower income neighbourhoods more often rated their health as fair/poor, and perceived their neighbourhood to be of poor quality. The strongest predictors for fair/poor health status were employment status, body mass index, neighbourhood satisfaction, and age, while modest predictors were annual household income, neighbourhood median income profile, and perceptions of neighbourhood safety. The unique contribution of this study is its demonstration that social gradients in self-rated health are observable between neighbourhoods of even modestly contrasting income profiles.

In May 2005, preliminary trial results pronouncing the effectiveness of Herceptin (trastuzumab) for treatment of early-stage breast cancer were disseminated at a high-profile scientific meeting. Herceptin was subsequently approved for use in the public healthcare systems of Canada and the United Kingdom, although the differences between the two decision timelines were stark. The authors compared UK and Canadian newspaper coverage of the Herceptin story to assess how it may have been "hyped" in each country. They analyzed a diverse sample of newspapers and coded clippings for reporters' framing of the drug's efficacy, costs and funding approval process. Canadian news coverage preceded formal publication of the trial results, while UK coverage mirrored major national events. Reporters in both countries used predominantly individualistic perspectives and framed Herceptin's efficacy in salutary terms. Framing of costs was more neutral in Canadian than in UK newspapers. Funding approval framing focused on inequitable access in the UK and timeliness in Canada. News coverage of drug access stories varies across jurisdictions in terms of intensity and some aspects of framing. Such variations likely reflect different journalistic practices and dominant political rhetoric. Greater attention should be given to the role that news coverage of drug access plays in shaping public opinion and policy action, especially when this coverage precedes scientific debate., (Copyright © 2009 Longwoods Publishing.)

November 2006 marked the 20-year anniversary of the Ottawa Charter for Health Promotion and Canada's Epp Report. Encapsulating the tenets of health promotion (HP), these publications articulated a vision for reducing health inequities, and described a policy framework for achieving this vision, respectively. These documents also triggered the launch of the population health (PH) field, focused on elucidating the empirical relationships between socioeconomic gradients and population health inequities. Over two decades, a rich HP/PH theoretical and evidentiary base on socioeconomic gradients in health has established. Yet, despite valuable contributions from Canadian researchers, insufficient headway has been made in this country to achieve the Charter's vision. There are numerous challenges to reducing population health inequities in Canada. Informational challenges include complexity of HP/PH evidence, and inadequate knowledge translation beyond traditional targets. Institutional challenges include the relative immunity of the healthcare sector to funding reductions, and the organization of policy responsibilities into silos. Concerns from non-healthcare sectors of 'health imperialism', and inter-governmental tensions are interest-related challenges, while ideological challenges include lack of media discourse on health inequities and a strong neo-liberal political climate. Gains have been made in Canada towards reducing health inequities. The HP/PH discourses are firmly entrenched in academic and policy spheres across the country, while several inter-sectoral policy initiatives are currently underway. HP/PH researchers could be more proactive in the knowledge-translation sphere by engaging other researchers outside of medicine and health, non-healthcare policy-makers, and the general public, vis-à-vis the media, on the health inequities knowledge base. Ultimately, significant and sustained progress will only be made if researchers and other champions recognize the inherently political aspect of their work and understand how to overcome ideologically driven resistance.

Pesticides with chlorpyrifos and endosulfan as active element are used for pest control on agricultural lands and are high-risk inputs in aquatic systems. The acute toxicity of these insecticides in the freshwater prawn Palaemonetes argentinus was evaluated. The results were used to determine the lowest observed-effect and no observed-effect concentrations. Individual growth of prawns in relation to chlorpyrifos and endosulfan exposure was analyzed. LC(50) values to chlorpyrifos and endosulfan exposure were 2.98 microg L(-1) and 14.10 at 24 hours and 0.49 microg L(-1) and 6.28 microg L(-1) at 96 hours of exposure, respectively. The size increment of prawns was the same in all treatments; cephalothorax length increased linearly per molt. The intermolt period was influenced by the toxic effect of pesticides during rearing time, and this decreased with the molt cycles compared with the normal growth pattern. The results suggest that juveniles of P. argentinus are sensitive to chlorpyrifos and endosulfan pollution.

The objective of this study was to explore the presence of ideological barriers to addressing local health inequalities in Hamilton, Ontario, Canada. A survey of active citizens revealed low levels of awareness of the social determinants of health (SDOH) framework, and some incongruence between understanding and attitudes towards the SDOH. Support for addressing health inequalities was associated with awareness of the SDOH framework, liberal value-systems, and a cluster of socio-demographic characteristics. Liberal leaning participants were also more politically active than their conservative counterparts. Ideological barriers included lack of SDOH awareness, narrow understandings of the relative influences of the SDOH, resistance to de-prioritizing healthcare, and conservative values. Advancement of a SDOH policy agenda should incorporate wider dissemination efforts to citizens and local service providers to increase support for this framework, and utilization of existing support and political engagement from liberal-leaning demographics.

News media effects on their audiences are complex. Four commonly cited effects are: informing audiences; agenda-setting; framing; and persuading. The release in autumn 2002 of two reports on options for reforming Canada's healthcare system attracted widespread media attention. We explored the potential for each of the four media effects by examining Canadian newspaper representation of this healthcare policy debate. Clippings were gathered from regional and national newspapers. Two data collection methodologies were employed: the first involved two staggered "constructed weeks" designed to capture thematic news framing styles; the second collected "intensive" or episodic coverage immediately following the report releases. Health reform articles with a financing and/or delivery focus were included. Using a codebook, articles were coded to track article characteristics, tone, healthcare sector and reform themes, and key actors. A greater quantity of episodic (n=341 clippings) versus thematic coverage (n=77) was documented. Coverage type did not vary significantly by newspaper, reporting source (e.g., staff reporter versus staff editorialist) or article type (e.g., news versus letter). Thematic articles were significantly shorter in length compared to episodic clippings. Episodic coverage tended to have a positive tone, while thematic coverage ranged in tone. Most coverage was general in scope. Sector-specific coverage favoured physician and hospital care--the two providers accorded privileged financing arrangements under Canada's universal, provincially administered health-insurance plans. Coverage of healthcare financing arrangements favoured broad discussions of publicly financed healthcare, federal-provincial governmental relations, and the Canada Health Act that governs provincial plans. Governmental actors and the political institutions that they represent were the dominant actors. Professional associations were also visible, but played a less dominant role. Given its non-specific scope, it is unclear how informative this coverage was. The large quantity and short duration of the episodic coverage, and the preponderance of governmental actors, suggests these newspapers acted as conduits for the policy agenda. Differences in framing styles were observed by coverage type, newspaper, reporting source, article length and type of article. Finally, the dominance of governmental actors provided these actors with numerous opportunities to persuade the public.

Background: High levels of stress-related illness are causing concern across industry. Against a background of impending legislative moves to try to improve this situation, there is a need to identify key work-related stressors. Police work tends to be regarded as inherently stressful because of the personal risk of exposure to confrontation and violence and the day-to-day involvement in a variety of traumatic incidents. As a result, high levels of stress-related symptoms might be expected in this population., Objective: To examine the sources of stress-related symptoms within police officers and measure the prevalence of significant associated mental ill-health., Method: A cross-sectional questionnaire survey of a population of 1206 police officers was performed to assess levels of strain associated with a series of potential home and work related stressors. Participants were then split into low and high scoring groups on the basis of a General Health Questionnaire (GHQ) threshold score in order to identify those stressors most associated with mental ill-health effects., Results: Occupational stressors ranking most highly within the population were not specific to policing, but to organizational issues such as the demands of work impinging upon home life, lack of consultation and communication, lack of control over workload, inadequate support and excess workload in general. The high scoring group constituted 41% of the population and differed significantly from those with low scores in perception of all stressors, ranking both personal and occupational stressors more highly, and from personality constraints appeared significantly more 'stress-prone'. A significant association between gender and mental ill-health was found, with females more likely to score more highly on the GHQ than males., Conclusion: This study confirms previous findings of organizational culture and workload as the key issues in officer stress. Given that the degree of symptomatology appears to be worsening, management action is required. Further research is indicated within the police population into a possible increased susceptibility in female officers.

Television viewing at home by 50 individuals in 5 age groups (2-, 5-, 8-, 12-year-olds, and adults) was recorded on 1-s time-lapse videotapes over 10-day periods. Coding was based on 5-min point samples. Analysis examined looking at the TV screen in relation to the visual presence of the features cuts, movement, animation, man, woman, child, and nonhuman; content features were child vs. adult programming and overt purposeful character behavior. Cuts, movement, and overt purposeful character behavior were positively related to looking independent of child vs. adult programming. Associations with looking for the remaining features depended on the viewer's age or sex or type of content within which they occurred.

Increasing isolation of Cryptosporidium, Cyclospora, and microsporidia from immunocompromised patients with severe diarrhea has prompted study of these organisms. Only recently recognized as human pathogens, they have also been associated with several waterborne outbreaks of diarrhea in immunocompetent individuals. Cryptosporidium and Cyclospora have been shown to be transmitted through fecally contaminated food and water. The mode of transmission for microsporidia is still unclear. While the life cycle and pathogenesis of Cryptosporidium are beginning to be understood, the microsporidia and Cyclospora are less well elucidated. The laboratory diagnosis of these protozoa is difficult. The routine ova and parasites screen does not include screening for them. Many microscopic methods, including wet mounts, modified acid-fast and trichrome stains, and immunofluorescence methods have been shown to be effective screening methods in the hands of experienced microscopists. Enzyme immunoassay and polymerase chain reaction methods also show promise. The proper identification of these pathogens rests with well-trained laboratory personnel. As appropriate treatment differs for each genus, communication between the laboratory and the physician is vital to the recovery of the patient.

Waterborne transmission of Cryptosporidium, Cyclospora, and Giardia has been associated with numerous recent outbreaks of diarrheal disease. Epidemiologic evidence shows that many community-acquired infections originate from public water sources. Drinking water, even when chlorinated and filtered, has been implicated in several outbreaks. Cryptosporidium and Cyclospora are resistant to chlorine. Giardia cysts are not killed immediately by chlorine and are less susceptible than most other organisms. Swimming pools and other recreational waters have also been implicated as transmission sources. All 3 organisms pose a challenge to the water industry, as they are difficult to detect in water when small numbers of cysts or oocysts are present. Small numbers of these organisms can cause disease; therefore, the clinical laboratory must be vigilant in screening, identifying, and reporting outbreaks of illness due to these protozoa.

The heterogeneous expression of lymphocyte homing receptors (HR) by the (CD45RA(low)/RO(high)) memory/effector T cell population in the human is thought to define subsets with tissue-selective recirculatory potential. To investigate further the localization characteristics of these T cells, we used multiparameter flow cytometry to quantitate T cell subsets defined by expression of the skin-selective HR called the cutaneous lymphocyte-associated antigen (CLA), the peripheral lymph node (PLN) HR L-selectin, the mucosal-associated HR alpha 4 beta 7-integrin, and the mucosal-associated adhesion molecule alpha e beta 7-integrin in either cutaneous or pulmonary immune effector sites and corresponding peripheral blood. Compared to peripheral blood, skin T cells were highly enriched for the CLA+/L-selectin+/alpha e beta 7-integrin- memory/effector subset, whereas lung memory/effector T cells were predominantly CLA-to low L-selectin-, and almost half were alpha e beta 7-integrin+. alpha 4 beta 7-integrin expressing memory/effector T cells were diminished in both skin and lung, suggesting that this HR is not a major participant in determining localization specificity in either of these sites. The characteristic pulmonary T cell HR phenotype did not significantly differ between the normal subjects and those with pulmonary inflammatory disease, and did not correlate with markers of T cell activation. Induction of a rapid up-regulation of pulmonary inflammation via intrabronchial allergen challenge in asthmatic patients tended to decrease localization specificity, resulting in a more general importation of memory/effector subsets. Taken together, these results suggest that tissue microenvironments play a major role in determining the character of local T cell infiltrates via their ability to import and retain memory/effector subsets selectively or, more generally, depending on the intensity of local inflammatory stimuli.

The aim of the present study was to investigate the role of the peripheral cholinergic system in patients with sympathetically maintained pain (SMP). Thirty-three patients with SMP were given Bier's block with 0.6 mg of atropine in 10 ml of saline or 10 ml of saline in a randomised double-blind manner. Pain intensity, pain relief and mood were assessed before and after each block using the visual analogue scale (VAS). In addition pain intensity was assessed at the same time using a categorical scale (CS). There was at least 1 week between each injection, and during this week the patients reported their pain intensity daily, using the CS. Three patients failed to complete both wings of the study and thus the results of the remaining 30 patients were analysed using the Mann-Whitney U test and the Wilcoxon signed-rank test. No significant difference was found between atropine and saline on any parameter.

Conventional virgin lymphocytes of a given class show relatively homogeneous recirculation through secondary lymphoid tissues, whereas memory/effector populations are composed of distinct subsets with differential, often tissue-selective migratory capability. In keeping with these observations, CD45RAhigh/ROlow "virgin" T cells in human peripheral blood uniformly express the peripheral lymph node homing receptor (HR) L-selectin, whereas among the CD45RAlow/ROhigh "memory/effector" subset, the expression of this HR is bimodal. To investigate the mechanisms responsible for the generation of memory/effector T cell subsets with differential homing potential, we developed a multiparameter flow cytometric technique that defines a common pathway of post-thymic T cell differentiation in secondary lymphoid tissues. Our analyses indicate that the virgin to memory T cell transition is characterized by a stepwise, unidirectional progression through distinct CD45RA+/RO+ intermediates that allow the in vivo discrimination of early, middle, and late transitional T cells. In normal peripheral blood, few T cells with a transitional phenotype are identified, but in secondary lymphoid tissues, 2 to 10% of T cells have this phenotype, including those CD45RA+ T cells that 1) are morphologically blasts, 2) are in S or G2/M phase of the cell cycle, or 3) express activation Ag. General adhesion molecules (LFA-1, LFA-3, ICAM-1) are uniformly up-regulated concordant with changes in T cell expression of CD45RA/RO in all tissues examined. Early in the transition, L-selectin is also uniformly up-regulated, but in subsequent stages, T cell expression of this HR is preferentially down-regulated in mucosal lymphoid tissues, and retained in peripheral lymph node. Differential regulation of L-selectin can also be demonstrated in vitro by the activation of virgin T cells in the presence of specific cytokines--IL-2 induces L-selectin down-regulation, whereas IL-6 and particularly TGF-beta 1 promote L-selectin up-regulation. Taken together, these findings support the hypothesis that local microenvironments within particular secondary lymphoid tissues influence HR expression at the time of CD45RA/RO conversion, and thereby contribute to the formation of CD45RAlow/ROhigh memory/effector T cell populations with tissue-selective homing behavior.

Recent work indicates that a novel homing receptor (HR)/endothelial ligand pair--the cutaneous lymphocyte-associated Ag (CLA) and E-selectin--is involved in targeting a unique skin-associated subpopulation of memory T cells to cutaneous sites of chronic inflammation. To investigate the regulatory mechanisms responsible for the generation of a memory T cell subset with skin-selective homing capability, we used multiparameter flow cytometry to assess the expression of CLA on T cells during initial T cell activation in secondary lymphoid tissues (the virgin to memory transition), and upon reactivation in skin. Our analyses indicate that in vivo induction of CLA (and E-selectin-binding ability) first occurs during the virgin to memory transition, and is regulated in a highly tissue-selective manner. The frequency of CLA expression on CD45RA+/RO+ transitional T cells within skin-associated peripheral lymph nodes was > fivefold higher than within the mucosal microenvironment of the appendix. In keeping with its role as a skin-selective homing receptor, levels of cell-surface CLA on T cells obtained from cutaneous blisters overlying delayed-type hypersensitivity sites were a mean 23-fold higher than on corresponding peripheral blood T cells, including all time points of lesional evolution. However, comparisons of CLA expression on resting vs activated skin blister T cells (HLA-DR - vs +, respectively) indicated that CLA expression, which is already quite high on the resting subset, appeared to be further up-regulated upon activation in skin. The critical involvement of local microenvironments in the regulation of CLA expression was also supported by in vitro studies demonstrating the necessity of specific secondary signals for the induction of CLA glycoproteins on mitogen-activated T cells. CLA up-regulation on both the virgin and memory T cell subsets was dependent on the presence of TGF-beta 1 (or, to a lesser extent, IL-6), but not a wide variety of other cytokines. Thus, the development of the CLA+ memory T cell subset is likely a product of the cumulative experience of those T cells with respect to local microenvironments at previous sites of activation, perhaps involving differential availability of bioactive TGF-beta 1 and/or IL-6 (both cytokines produced in skin). Repeated activation in skin or skin-associated peripheral lymph nodes may act to reinforce CLA expression on T cells functionally-associated with skin, and thus enhance the functional efficiency of these cells by preferentially focusing their recirculation to the skin or related sites.

Mandibular epithelia and mesenchyme from chick embryos of Hamburger and Hamilton (H.H.) stage 18-25 were cultured intact, in isolation, or in recombinations in the presence or absence of 5-40 ng/ml epidermal growth factor (EGF). 3H-thymidine labelling demonstrated that mesenchyme influenced epithelial mitotic activity and vice versa. EGF can substitute for the epithelial effect. The stimulation of mesenchymal proliferation by H.H. 18 and 22 epithelia correlated with high levels of epithelial proliferation. Epithelial proliferation was low at H.H. 25 and unaffected by mesenchyme or by EGF. Epithelial stimulation of mesenchymal proliferation began earlier (H.H. 18) than did mesenchymal stimulation of epithelial proliferation (H.H. 22); i.e., within the ages tested, the epithelium initiated these reciprocal mitogenic interactions. That epithelial dependence on mesenchyme coincided with epithelial bone-evoking properties, suggested a) that mesenchyme promotes or maintains epithelial bone-promoting activity and b) that the critical differentiative influence of epithelium on mesenchyme is a mitogenic one. The temporal correlation between a sharp decline in mesenchymal proliferation and termination of the osteogenic epithelial-mesenchymal interaction at H.H. 25 further supports a connection between epithelial maintenance of mesenchymal proliferation and epithelial evocation of osteogenesis.

The kinetic interactions of inhibitin, a peptide isolated from cultured leukaemic promyelocytes, with erythrocyte Na+/Na+ and Na+/Li+ exchanges have been investigated. Inhibitin (1 microM) reduced the ouabain- and bumetanide-resistant sodium efflux and influx by equivalent amounts indicating an inhibitin-sensitive exchange component of 0.52 mmol/l per h. This value was not significantly different from that measured as the difference in sodium-rich (140 mM) and sodium-free media (0.49 mmol/l per h). Similarly, the inhibitin-sensitive lithium efflux was equivalent to the sodium/lithium countertransport component (0.36 vs. 0.34 mmol/l per h), indicating that both exchanges were mediated by the same transport process, which is inhibitin-sensitive. The dose-response curve revealed the presence of a single inhibitin binding site per exchanger with a Ki of 2.10(-7) M. In kinetic inhibition studies, inhibitin (0.1 microM) decreased the Vmax of ouabain- and bumetanide-resistant sodium efflux with no effect on the Km for external sodium, i.e., inhibitin displayed a non-competitive mechanism of action. These findings indicate that inhibitin interacts with the Na+(Li+)i/Nao+ exchanger at a site distinct from the sodium binding site.