Can systemic administration of drag reducing agents reduce the risk of metastasizing after cancer surgery? A hydrodynamics based hypothesis

The human blood and lymphatic systems serve as transport media for circulating tumor cells. Hydrodynamic analysis suggests that the systemic administration of drag-reducing agents (DRA) in nanomolar concentrations may reduce the risk of metastasizing of circulating tumor cells. After testing this hypothesis on animal models, it could become a new complementary post-operative treatment for cancer patients or even replace classical cancer aftercare for patients with severe intolerance against chemo- or radio-therapy. Our approach is based on the following considerations:- Circulating tumor cells need for settling down a favorable environment in terms of nutrition and after settling also in its first stage of development an extra nutrient supply in order to survive and grow finally into the interstice.- The attachment of circulating tumor cells therefore tends to occur at sites in the human circulatory system characterized by localized turbulence, which enhances the mass transfer of nutrients, e.g., at sites of vessel branching and bending with plasma skimming.- Also restrictions to blood flow, such as plaques (atherosclerosis), red blood cell (RBC) rouleaux, and even tumor cells in its first stage of development attached to the inner vessel wall may produce local vortices that increase mass transfer, i.e., food supply.- DRA have the ability to smooth (laminarise) localized turbulence in the circulatory system and to reduce mass transfer. The systemic administration of DRA could therefore serve in a first step to defuse potential settling points, i.e., to make them harmless.- Depriving freshly settled down tumor cells of their required nutrient levels should therefore in a second step reduce the probability of creating metastatic tumors, and may even lead to its starvation-induced death before they grow into the interstice.In the first part of our essay we demonstrate how flow constrictions decrease the mean blood flow velocity, wall shear rates, and Reynolds numbers respectively, and increase the friction factor.Experimentally derived apparent viscosity data from literature will be used to determine the probability of RBC rouleaux formation. This is of importance since RBC rouleaux are typically associated with turbulent blood flow patterns. An increase in apparent viscosity at low flow rates will be attributed to the formation of RBC rouleaux.In part two we discuss the application of the Lockhart/Martinelli method to determine the pressure drop in blood vessels. The objective is to determine a mass transfer coefficient characterizing the mass transfer between the center and the wall of both healthy and constricted blood vessels. This coefficient indicates the nutrient supply available to tumor cells in its first stage of development under different flow conditions and shows the effect of administration of DRA.Our hydrodynamic approach contrasts with previous studies of the possible benefits of DRA administration, which were focused on improving blood supply. We emphasize the reduction of the mass transfer rate as a tool to withhold turbulence induced supplementary food supply to circulating tumor cells in the process of settling and in its first stage of development.Due to the hypothetical character of our approach and the possibility of unexpected side effects when administrating DRA (including their mechanical degradation products) animal models are indispensable before clinical trials

Landowner Cooperative Key to Success in the Bee Ridge Quail Focus Area

The Missouri Department of Conservation (MDC) began establishing Quail Focus Areas (QFAs) on private lands in 2004. The goal of QFAs is to increase and expand quail habitat management efforts around a core area. Because most (93%) of the landscape of Missouri, USA is in private ownership, habitat improvement programs on private lands have greater potential to impact quail populations than on public lands alone. A motivated group of landowners led the charge to begin habitat improvement efforts in the Bee Ridge QFA. This group was instrumental in starting earlier monitoring efforts to determine whether habitat improvements were leading to increased northern bobwhite (Colinus virginianus; hereafter, bobwhite) numbers. In fall 2017, MDC staff began monitoring bobwhite and songbirds in a portion of the Bee Ridge QFA in Knox County, Missouri and in a control area (without habitat management for bobwhite). This effort is part of the Coordinated Implementation Plan developed by the National Bobwhite Technical Committee as a part of the National Bobwhite Conservation Initiative. The goal of the monitoring plan is to document whether quail habitat management can achieve sustainable bobwhite populations within 5–10 years. We selected a 2,225-ha portion of the Bee Ridge QFA where habitat management for quail has been conducted through efforts by landowners and MDC staff. Point transect surveys are conducted at 46 250-m radius points in spring for bobwhite and songbirds and at 12 500-m radius points in fall for bobwhite coveys. Bobwhite densities ranged from 0.23 bobwhite/ha (95% credible interval [CrI] = 0.14–0.35) to 0.27 bobwhite/ha (95% CrI = 0.15–0.43) in the focus area and 0.03 bobwhite/ha (95% CrI = 0.01–0.08) to 0.06 bobwhite/ha (95% CrI = 0.01–0.15) in the control area from 2013 through 2019. Landowners working together to implement recommended habitat management practices resulted in greater quail and songbird numbers in the focus area, compared to the control area

Do health systems delay the treatment of poor children? A qualitative study of child deaths in rural Tanzania.

Child mortality remains one of the major public-health problems in Tanzania. Delays in receiving and accessing adequate care contribute to these high rates. The literature on public health often focuses on the role of mothers in delaying treatment, suggesting that they contact the health system too late and that they prefer to treat their children at home, a perspective often echoed by health workers. Using the three-delay methodology, this study focus on the third phase of the model, exploring the delays experienced in receiving adequate care when mothers with a sick child contact a health-care facility. The overall objective is to analyse specific structural factors embedded in everyday practices at health facilities in a district in Tanzania which cause delays in the treatment of poor children and to discuss possible changes to institutions and social technologies. The study is based on qualitative fieldwork, including in-depth interviews with sixteen mothers who have lost a child, case studies in which patients were followed through the health system, and observations of more than a hundred consultations at all three levels of the health-care system. Data analysis took the form of thematic analysis. Focusing on the third phase of the three-delay model, four main obstacles have been identified: confusions over payment, inadequate referral systems, the inefficient organization of health services and the culture of communication. These impediments strike the poorest segment of the mothers particularly hard. It is argued that these delaying factors function as 'technologies of social exclusion', as they are embedded in the everyday practices of the health facilities in systematic ways. The interviews, case studies and observations show that it is especially families with low social and cultural capital that experience delays after having contacted the health-care system. Reductions of the various types of uncertainty concerning payment, improved referral practices and improved communication between health staff and patients would reduce some of the delays within health facilities, which might feedback positively into the other two phases of delay

Does improved functional performance help to reduce urinary incontinence in institutionalized older women? a multicenter randomized clinical trial

<p>Abstract</p> <p>Background</p> <p>Urinary incontinence (UI) is a major problem in older women. Management is usually restricted to dealing with the consequences instead of treating underlying causes such as bladder dysfunction or reduced mobility.</p> <p>The aim of this multicenter randomized controlled trial was to compare a group-based behavioral exercise program to prevent or reduce UI, with usual care. The exercise program aimed to improve functional performance of pelvic floor muscle (PFM), bladder and physical performance of women living in homes for the elderly.</p> <p>Methods</p> <p>Twenty participating Dutch homes were matched and randomized into intervention or control homes using a random number generator. Homes recruited 6–10 older women, with or without UI, with sufficient cognitive and physical function to participate in the program comprising behavioral aspects of continence and physical exercises to improve PFM, bladder and physical performance. The program consisted of a weekly group training session and homework exercises and ran for 6 months during which time the control group participants received care as usual. Primary outcome measures after 6 months were presence or absence of UI, frequency of episodes (measured by participants and caregivers (not blinded) using a 3-day bladder diary) and the Physical Performance Test (blinded). Linear and logistic regression analysis based on the Intention to Treat (ITT) principle using an imputed data set and per protocol analysis including all participants who completed the study and intervention (minimal attendance of 14 sessions).</p> <p>Results</p> <p>102 participants were allocated to the program and 90 to care as usual. ITT analysis (n = 85 intervention, n = 70 control) showed improvement of physical performance (intervention +8%; control −7%) and no differences on other primary and secondary outcome measures. Per protocol analysis (n = 51 intervention, n = 60 control) showed a reduction of participants with UI (intervention −40%; control −28%) and in frequency of episodes (intervention −51%; control −42%) in both groups; improvement of physical performance (intervention + 13%; control −4%) was related to participation in the exercise program.</p> <p>Conclusions</p> <p>This study shows that improving physical performance is feasible in institutionalized older women by exercise. Observed reductions in UI were not related to the intervention. [Current Controlled Trials ISRCTN63368283]</p

Multiple Lines of Evidence Risk Assessment of Terrestrial Passerines Exposed to PCDFs and PCDDs in the Tittabawassee River Floodplain, Midland, Michigan, USA

A site-specific multiple lines of evidence risk assessment was conducted for house wrens (Troglodytes aedon) and eastern bluebirds (Sialia sialis) along the Tittabawassee River downstream of Midland, Michigan, where concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in flood-plain soils and sediments are greater compared to upstream areas and some of the greatest anywhere in the world. Lines of evidence supporting the population-level assessment endpoints included site-specific dietary- and tissue-based exposure assessments and population productivity measurements during breeding seasons 2005–2007. While a hazard assessment based on site-specific diets suggested that populations residing in the downstream floodplain had the potential to be affected, concentrations in eggs compared to appropriate toxicity reference values (TRVs) did not predict a potential for population-level effects. There were no significant effects on reproductive success of either species. The most probable cause of the apparent difference between the dietary- and tissue-based exposure assessments was that the dietary-based TRVs were overly conservative based on intraperitoneal injections in the ring-necked pheasant. Agreement between the risk assessment based on concentrations of PCDFs and PCDDs in eggs and reproductive performance in both species supports the conclusion of a small potential for population-level effects at this site

Optimal central-place foraging by beavers: Tree-size selection in relation to defensive chemicals of quaking aspen

At a newly occupied pond, beavers preferentially felled aspen smaller than 7.5 cm in diameter and selected against larger size classes. After one year of cutting, 10% of the aspen had been cut and 14% of the living aspen exhibited the juvenile growth form. A phenolic compound which may act as a deterrent to beavers was found in low concentrations in aspen bark, and there was no significant regression of relative concentration of this compound on tree diameter. At a pond which had been intermittently occupied by beavers for over 20 years, beavers selected against aspen smaller than 4.5 cm in diameter, and selected in favor of aspen larger than 19.5 cm in diameter. After more than 28 years of cutting at this site, 51% of the aspen had been cut and 49% of the living aspen were juvenileform. The phenolic compound was found in significantly higher concentrations in aspen bark than at the newly occupied site, and there was a significant negative regression of relative concentration on tree diameter. The results of this study show that responses to browsing by trees place constraints on the predictive value of standard energy-based optimal foraging models, and limitations on the use of such models. Future models should attempt to account for inducible responses of plants to damage and increases in concentrations of secondary metabolites through time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47775/1/442_2004_Article_BF00379963.pd