Purification of three rat atrial natriuretic factors and their amino acid composition

AbstractA natriuretic factor has been described in the specific granules of rat atria. We have purified three factors which seem to be low-Mr peptides. They have been purified by means of acid extraction, octadecyl Sep-Pak cartridges, and chromatography on Bio-Gel P-10, CM Bio-Gel A, Mono S and reverse-phase high-performance liquid chromatography columns. The factors contain 26, 31 and 33 amino acids and may have been partially degraded during isolation. They are all 3 biologically active and the shorter one is the most active with a specific activity of 450000 units/mg

Group-based Funeral Insurance in Ethiopia and Tanzania

A funeral is a costly occasion. This paper studies indigenous insurance institutions developed to cope with the high costs of funerals, based on evidence from rural areas in Tanzania and Ethiopia. These institutions are based on well-defined rules and regulations, often offering premium-based insurance for funeral expenses. Increasingly, they are also offering other forms of insurance and credit to cope with hardship. The paper argues that the characteristics and inclusiveness of these institutions make them well-placed as models to broaden insurance provision and other developmental activities in these communities. The history of these institutions is characterised by a resistance to attempts of political capture, and helps to understand their apparent resistance to engage more broadly with NGOs and government agencies. As a result, any attempt to expand their activities will have to be done cautiously.Risk-Sharing, Insurance, Africa, Ethiopia, Tanzania

Membership Based Indigenous Insurance Associationsin Ethiopia and Tanzania

Indigenous insurance associations are a prevalent form of membership based organisations of the poor, at least in the rural areas in Ethiopia and Tanzania surveyed by the authors. Results show how villagers with few links to any formal kind of insurance market have established membership-based indigenous insurance associations to protect themselves against unexpected expenditures, mainly for funerals and hospitalisation. Many of these institutions tend to co-exist within the same community and are based on well-defined rules and regulations, well beyond informal reciprocal relations. They tend to offer premium-based insurance for funeral expenses, as well as, in many cases, other forms of insurance and credit to help address hardship. These groups are completely owned and managed by their members. They were locally initiated and have been continually developing through the actions of their own members, without involvement from the government or donors. Using detailed group membership data linked to household survey data we show that (i) these institutions are widely prevalent in the surveyed areas, (ii) households typically belong to several groups at the same time, (iii) they display a large degree of inclusiveness and (iv) they insure an important part of some shocks, but still leave households prone to the effects of risk

Effect of selective ET A receptor blockade on natriuretic peptide gene expression in DOCA-salt hypertension

To determine the role of endothelin-1 (ET-1) in the upregulation of atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) observed in deoxycorticosterone acetate (DOCA)-salt hypertension, the selective ET-1 type-A receptor (ETA) antagonist ABT-627 was chronically administered to normal controls and hypertensive rats. Chronic ETA blockade in DOCA-salt-treated rats prevented the increase in blood pressure and circulating natriuretic protein (NP) levels and partially prevented left ventricular hypertrophy. The changes observed in NP gene expression in the atria were not affected by ABT-627. In the ventricles, ABT-627 reduced NP gene expression. Rats receiving the ETA antagonist alone showed reduced left ventricular NP gene expression. ABT-627 did not affect ventricular collagen III gene expression but enhanced left ventricular α-myosin heavy chain expression. These findings suggest that in vivo, ventricular but not atrial NP production is regulated by ET-1. This difference in response between atrial and ventricular NP gene expression to ETA receptor blockade is similar to that observed by us after applying angiotensin-converting enzyme inhibitors in other hypertensive models. In general therefore, atrial NP gene expression may not be as sensitive to the endocrine environment as is ventricular NP gene expression.Fil: Bianciotti, Liliana Graciela. University of Ottawa; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: de Bold, Adolfo. University of Ottawa; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

Transcriptional analysis of the mammalian heart with special reference to its endocrine function

<p>Abstract</p> <p>Background</p> <p>Pharmacological and gene ablation studies have demonstrated the crucial role of the endocrine function of the heart as mediated by the polypeptide hormones ANF and BNP in the maintenance of cardiovascular homeostasis. The importance of these studies lies on the fact that hypertension and chronic congestive heart failure are clinical entities that may be regarded as states of relative deficiency of ANF and BNP. These hormones are produced by the atrial muscle cells (cardiocytes), which display a dual secretory/muscle phenotype. In contrast, ventricular cardiocytes display mainly a muscle phenotype. Comparatively little information is available regarding the genetic background for this important phenotypic difference with particular reference to the endocrine function of the heart. We postulated that comparison of gene expression profiles between atrial and ventricular muscles would help identify gene transcripts that underlie the phenotypic differences associated with the endocrine function of the heart.</p> <p>Results</p> <p>Comparison of gene expression profiles in the rat heart revealed a total of 1415 differentially expressed genes between the atria and ventricles based on a 1.8 fold cut-off. The identification of numerous chamber specific transcripts, such as ANF for the atria and Irx4 for the ventricles among several others, support the soundness of the GeneChip data and demonstrates that the differences in gene expression profiles observed between the atrial and ventricular tissues were not spurious in nature. Pathway analysis revealed unique expression profiles in the atria for G protein signaling that included Gα_o1, Gγ₂and Gγ₃, AGS1, RGS2, and RGS6 and the related K⁺channels GIRK1 and GIRK4. Transcripts involved in vesicle trafficking, hormone secretion as well as mechanosensors (e.g. the potassium channel TREK-1) were identified in relationship to the synthesis, storage and secretion of hormones.</p> <p>Conclusion</p> <p>The data developed in this investigation describes for the first time data on gene expression particularly centred on the secretory function of the heart. This provides for a rational approach in the investigation of determinants of the endocrine of the heart in health and disease.</p

Driver hand positions on the steering wheel while merging into motorway traffic

It has been suggested that a driver's hand position on the steering wheel can reflect the perceived risk of the road context (Walton, D., & Thomas, J. A. (2005). Naturalistic observations of driver hand positions. Transportation Research Part F, 8. 229-238, Thomas, J. A., & Walton, D. (2007). Measuring perceived risk: Self-reported and actual hand positions of SUV and car drivers. Transportation Research Part F, 10, 201-207). These original studies were based on field observations where only a part of the steering wheel could be viewed. In the present study hand positions were observed in a driving simulator during the performance of a demanding task: merging into motorway traffic. In the current study the whole steering wheel could be observed and hand positions were classified in three categories: high control, medium control, and low control. Differences in hand position between different traffic conditions were limited, and hand position did not correlate with self-reported risk or self-reported mental effort, but changes in hand positions do seem to be associated with changes in workload demand. It is therefore concluded that hand position can give some information about mental workload. (C) 2010 Elsevier Ltd. All rights reserved

Non-destructive evaluation of railway trackbed ballast

The “green agenda” combined with highway congestion has accelerated the demand for increased freight and passenger travel on the world’s railways. These increases have driven demand for more efficient and rapid investigation of trackbed ballast. Network Rail and other rail infrastructure operators spend significant financial sums on inspecting, tamping, adjusting, cleaning, and replacing trackbed ballast. Such maintenance is often to the detriment of normal network operation. Industry requires a method of ballast evaluation that is non-intrusive, cheap, can appraise long stretches of track in a short period of time, and give a fingerprinting result from which time-to-maintenance can be calculated and planned. Thus, the aim was to develop evaluation methods using non-destructive testing techniques. A 10-year old full-scale trackbed composed of variously fouled ballast was re-visited and used for experimentation. The condition of the ballast was calculated using the Ionescu Fouling Index. Earlier research at the University of Edinburgh enabled researchers worldwide to characterise ballast using ground penetrating radar (GPR). This research was repeated, validated and taken forward in a series of GPR experiments on the trackbed using a range of antennas from 500MHz to 2.6GHz. New "scatter" metrics were developed to determine ballast condition from the GPR waveforms. These metrics were then used to predict the Ionescu Fouling Index with a correlation coefficient greater than 0.9. One of the current approaches to evaluating the stiffness of railway ballast is to use a Falling Weight Deflectometer (FWD). The viability of using a Prima 100 mini-FWD on railways to measure stiffness was determined and deemed to be ineffective on ballast. The applicability of the impulse response technique on railways was determined. An instrumented hammer was used to excite the ballast, with a geophone measuring the response. The Frequency Response Function of this was successfully correlated with the Ionescu Fouling Index with a correlation coefficient also greater than 0.9. Finally, using GPR data and measured stiffness data collected by Banverket, Sweden, a numerical model to successfully relate radar responses to stiffness was developed