Evidence for RNA transport in rat optic nerve

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66066/1/j.1471-4159.1969.tb08995.x.pd

Construction and analysis of causally dynamic hybrid bond graphs

Engineering systems are frequently abstracted to models with discontinuous behaviour (such as a switch or contact), and a hybrid model is one which contains continuous and discontinuous behaviours. Bond graphs are an established physical modelling method, but there are several methods for constructing switched or ‘hybrid’ bond graphs, developed for either qualitative ‘structural’ analysis or efficient numerical simulation of engineering systems. This article proposes a general hybrid bond graph suitable for both. The controlled junction is adopted as an intuitive way of modelling a discontinuity in the model structure. This element gives rise to ‘dynamic causality’ that is facilitated by a new bond graph notation. From this model, the junction structure and state equations are derived and compared to those obtained by existing methods. The proposed model includes all possible modes of operation and can be represented by a single set of equations. The controlled junctions manifest as Boolean variables in the matrices of coefficients. The method is more compact and intuitive than existing methods and dispenses with the need to derive various modes of operation from a given reference representation. Hence, a method has been developed, which can reach common usage and form a platform for further study

“Health regains but livelihoods lag”: findings from a study with people on ART in Zambia and Kenya

International audienceAlthough ART is increasingly accessible and eases some stresses, it creates other challenges including the importance of food security to enhance ART-effectiveness. This paper explores the role livelihood strategies play in achieving food security and maintaining nutritional status among ART patients in Kenya and Zambia. Ongoing quantitative studies exploring adherence to ART in Mombasa, Kenya (n=118) and in Lusaka, Zambia (n= 375) were used to identify the relationship between BMI and adherence; an additional set of in-depth interviews with people on ART (n=32) and members of their livelihood networks (n=64) were undertaken. Existing frameworks and scales for measuring food security and a positive deviance approach was used to analyse data. Findings show the majority of people on ART in Zambia are food insecure; similarly most respondents in both countries report missing meals. Snacking is important for dietary intake, especially in Kenya. Most food is purchased in both countries. Having assets is key for achieving livelihood security in both Kenya and Zambia. Food supplementation is critical to survival and for developing social capital since most is shared amongst family members and others. Whilst family and friends are key to an individual's livelihood network, often more significant for daily survival is proximity to people and the ability to act immediately, characteristics most often found amongst neighbours and tenants. In both countries findings show that with ART health has rebounded but livelihoods lag. Similarly, in both countries respondents with high adherence and high BMI are more self-reliant, have multiple income sources and assets; those with low adherence and low BMI have more tenuous livelihoods and were less likely to have farms/gardens. Food supplementation is, therefore, not a long-term solution. Building on existing livelihood strategies represents an alternative for programme managers and policy makers as do other strategies including supporting skills and asset accumulation

HIV-1 Enhancing Effect of Prostatic Acid Phosphatase Peptides Is Reduced in Human Seminal Plasma

We recently reported that HIV-1 infection can be inhibited by innate antimicrobial components of human seminal plasma (SP). Conversely, naturally occurring peptidic fragments from the SP-derived prostatic acid phosphatase (PAP) have been reported to form amyloid fibrils called “SEVI” and enhance HIV-1 infection in vitro. In order to understand the biological consequence of this proviral effect, we extended these studies in the presence of human SP. PAP-derived peptides were agitated to form SEVI and incubated in the presence or absence of SP. While PAP-derived peptides and SEVI alone were proviral, the presence of 1% SP ablated their proviral activity in several different anti-HIV-1 assays. The anti-HIV-1 activity of SP was concentration dependent and was reduced following filtration. Supraphysiological concentrations of PAP peptides and SEVI incubated with diluted SP were degraded within hours, with SP exhibiting proteolytic activity at dilutions as high as 1∶200. Sub-physiological concentrations of two prominent proteases of SP, prostate-specific antigen (PSA) and matriptase, could degrade physiological and supraphysiological concentrations of PAP peptides and SEVI. While human SP is a complex biological fluid, containing both antiviral and proviral factors, our results suggest that PAP peptides and SEVI may be subject to naturally occurring proteolytic components capable of reducing their proviral activity