Parametrical modeling and design optimization of blood plasma separation device with microchannel mechanism

This paper presents an analysis of biofluid behavior in a T-shaped microchannel device and a design optimization for improved biofluid performance in terms of particle liquid separation. The biofluid is modeled with single phase shear rate non-Newtonian flow with blood property. The separation of red blood cell from plasma is evident based on biofluid distribution in the microchannels against various relevant effects and findings, including Zweifach-Fung bifurcation law, Fahraeus effect, Fahraeus-Lindqvist effect and cell free phenomenon. The modeling with the initial device shows that this T-microchannel device can separate red blood cell from plasma but the separation efficiency among different bifurcations varies largely. In accordance with the imbalanced performance, a design optimization is conducted. This includes implementing a series of simulations to investigate the effect of the lengths of the main and branch channels to biofluid behavior and searching an improved design with optimal separation performance. It is found that changing relative lengths of branch channels is effective to both uniformity of flow rate ratio among bifurcations and reduction of difference of the flow velocities between the branch channels, whereas extending the length of the main channel from bifurcation region is only effective for uniformity of flow rate ratio

Design, test and biological validation of microfluidic systems for blood plasma separation

Sample preparation has been described as the weak link in microfluidics. In particular, plasma has to be extracted from whole blood for many analysis including protein analysis, cell-free DNA detection for prenatal diagnosis and transplant monitoring. The lack of suitable devices to perform the separation at the microscale means that Lab On Chip (LOC) modules cannot be fully operated without sample preparation in a full-scale laboratory. In order to address this issue, blood flow in microchannels has been studied, and red blood cells behaviours in different geometrical environments have been classified. Several designs have been subsequently proposed to exploit some natural properties of blood flow and extract pure plasma without disturbing the cells. Furthermore, a high-level modelling method was developed to predict the behaviour of passive microfluidic networks. Additionally, the technique proposed provides useful guidance over the use of systems in more complex external environments. Experimental results have shown that plasma could be separated from undiluted whole blood in 10μm width microchannels at a flow rate of 2mL/hr. Using slightly larger structures (20μm) suitable for mass-manufacturing, diluted blood can be separated with 100% purity efficiency at high flow rate. An extensive biological validation of the extracted plasma was carried out to demonstrate its quality. To this effect Polymerase Chain Reaction (PCR) was performed to amplify targeted human genomic sequence from cell-free DNA present in the plasma. Furthermore, the influence of the sample dilution and separation efficiency on the amplification was characterised. It was shown that the sample dilution does have an influence on the amplification of house-keeping gene, but that amplification can be achieved even on high diluted samples. Additionally amplification can also be obtained on plasma samples with a range of separation efficiencies from 100% to 84%. In particular, two main points have been demonstrated (i) the extraction of plasma using combination of constrictions and bifurcations, (ii) the biological validation of the extracted plasma

Effect of fluid dynamics and device mechanism on biofluid behaviour in microchannel systems: modelling biofluids in a microchannel biochip separator

Biofluid behaviour in microchannel systems is investigated in this paper through the modelling of a microfluidic biochip developed for the separation of blood plasma. Based on particular assumptions, the effects of some mechanical features of the microchannels on behaviour of the biofluid are explored. These include microchannel, constriction, bending channel, bifurcation as well as channel length ratio between the main and side channels. The key characteristics and effects of the microfluidic dynamics are discussed in terms of separation efficiency of the red blood cells with respect to the rest of the medium. The effects include the Fahraeus and Fahraeus-Lindqvist effects, the Zweifach-Fung bifurcation law, the cell-free layer phenomenon. The characteristics of the microfluid dynamics include the properties of the laminar flow as well as particle lateral or spinning trajectories. In this paper the fluid is modelled as a single-phase flow assuming either Newtonian or Non-Newtonian behaviours to investigate the effect of the viscosity on flow and separation efficiency. It is found that, for a flow rate controlled Newtonian flow system, viscosity and outlet pressure have little effect on velocity distribution. When the fluid is assumed to be Non-Newtonian more fluid is separated than observed in the Newtonian case, leading to reduction of the flow rate ratio between the main and side channels as well as the system pressure as a whole

Fabrication and testing of microfluidic devices for blood cell separation

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Blood separation is a strategic preliminary step in preparation to on-chip biological analysis. Two microfluidic devices for on-chip blood separation are presented. Both devices will be integrated to form the separation module of a Lab on Chip for non-invasive prenatal diagnosis. In the first device, a blood plasma separator, the separation of blood cells from plasma is made possible in microchannels by bio-physical effects such as an axial migration effect and Zweifach-Fung bifurcation law. Behaviour of mussel and human blood suspensions were studied alongside the effect of different geometries. The second device aims to separate fetal nucleated red blood cells based on their magnetic susceptibility. Biocompatible materials are used in the manufacturing of both devices.The authors acknowledge the financial support of the Engineering and Physical Science Research Council (EPSRC) through the funding of the Grand Challenge Project ‘3DMintegration’, reference EP/C534212/1. This work has also been supported by the EPSRC through a Doctoral Training Account (DTA) and has been performed at the Microsystems Engineering Centre (MISEC), Heriot-Watt University, Edinburgh. We thank Tim Ryan and Phil Summersgill, Epigem Ltd. for the fabrication of the blood plasma chips. The fabrication work was carried out in the Fluence Microfluidics Application Centre supported by the DTI and the OneNE Regional Development Agency as part of the UK's MNT Network

Male-infant interactions in wild crested black macaques, Macaca nigra

Direct fitness is measured as the number of surviving offspring. Thus adult males may try to produce as many offspring as possible or to increase the survival of their offspring. Recent findings have shown the many potential benefits of fathers’ presence and support on infants’ development and survival. However, little is known about the influence of socio-ecological factors on male-infant interactions. The main aim of this thesis was therefore to investigate male-infant interactions in wild crested macaques (Macaca nigra). In particular, we aimed to examine the affiliative and agonistic interactions taking place in this species, along with the factors influencing these interactions and offspring survival. Data collection for this thesis took place in the Tangkoko-Duasudara Reserve in Sulawesi, Indonesia, on 3 wild groups of crested macaques. For the first study, data were collected on migrations, births, disappearances, and encounters between groups over 5 years. We analyzed the influence of socio-ecological factors (e.g. rainfall, alpha-male position takeover, and male hierarchy stability) on pre- and post-natal loss. The results showed that high infant mortality was mainly associated to male alpha-position takeover, which suggests that infanticide may indeed occur in this species. In addition, we found that female within-group competition for food sources and between-group resource defense influenced fetal and infant loss. Based on these findings, we were interested to see whether fathers protected their own offspring against male attacks. Thus, in the second study, we investigated the social determinants and characteristics of male-infant affiliations. Our results indicate that adult males and infants form preferential association, and that infants initiate the majority of male-infant affiliations. Infants initiated affiliations mainly towards a high ranking male or a male in a close relationship with their mother. In addition, infants affiliated mainly with adult males in the absence of their mother, while males affiliated mostly with infants when the infants‘ mother was present in proximity. Furthermore, males initiated affiliations towards an infant when they held a high rank or when they had a strong bond with the infant‘s mother. Interestingly, paternity did not affect male-infant affiliations. In conclusion, these studies provide insights in the specifics of both infant survival strategies and male reproductive strategies. In addition, we show that infants are active agents in establishing and maintaining preferential relationships with males. This thesis, thus, confirm that male-infant interactions, although rare, have a strong influence both on males’ and infants’ direct fitness.:Contents ........................................................................................................................................ 5 List of Figures .............................................................................................................................. 7 List of Tables ................................................................................................................................ 8 Summary ....................................................................................................................................... 9 Zusammenfassung .................................................................................................................. 13 1 General Introduction .......................................................................................................... 17 1.1 Infants and adult males in mammals ...................................................................... 18 1.2 Primate males’ use and abuse of infants ................................................................ 19 1.3 Male care and paternal care in primates ............................................................... 20 1.4 Crested macaques as study species ......................................................................... 21 1.5 Aims of this thesis ........................................................................................................... 23 2 Social and ecological factors influencing offspring survival in wild macaques ................................................................................................................................... 25 2.1 Abstract ............................................................................................................................... 26 2.2 Introduction ...................................................................................................................... 26 2.3 Methods .............................................................................................................................. 29 2.4 Results ................................................................................................................................. 34 2.5 Discussion .......................................................................................................................... 37 3 Mother-male bond, but not paternity, influences male-infant affiliation in wild crested macaques .......................................................................................................... 45 3.1 Abstract ............................................................................................................................... 46 3.2 Introduction ...................................................................................................................... 46 3.3 Methods .............................................................................................................................. 50 3.4 Results ................................................................................................................................. 58 3.5 Discussion .......................................................................................................................... 61 4 Thesis Conclusion ................................................................................................................ 71 Appendices ................................................................................................................................ 75 Supplementary figure and tables for Chapter 2 ......................................................... 76 Supplementary methods and tables for Chapter 3 ................................................... 79 Bibliography ............................................................................................................................. 83 Acknowledgements ................................................................................................................ 99 Contributions of co-authors .............................................................................................. 101 Curriculum vitae .................................................................................................................... 105 Publications and conference contributions ................................................................. 107 Selbstständigkeitserklärung ............................................................................................. 10

Bleu-blanc-cœur : a new agriculture approach dedicated to animal health, human health and environnent

Bleu-Blanc-Cœur est une association créée pour améliorer la qualité nutritionnelle et environnemen- tale de notre alimentation en apportant une nouvelle approche d’agriculture responsable. L’idée fondatrice de Bleu-Blanc-Cœur veut que : « pour bien nourrir les Hommes, il faut commencer par prendre soin de nos cultures et de la santé de nos animaux ». L’association fédère ainsi des agri- culteurs, entreprises, médecins, scientifiques et consommateurs. Bleu-Blanc-Cœur gère des cahiers des charges qui imposent une obligation de résultats décrivant une amélioration des qualités nutritionnelles des denrées alimentaires en lien avec des pratiques d’alimentation et d’élevage encadrées. La démarche repose sur un socle scientifique fort de 320 publications et 5 études cliniques ayant démon - tré l’intérêt de ces pratiques d’élevage pour la santé animale et humaine et aussi pour l’environnement. Bleu-Blanc-Cœur est une démarche d’intérêt nutritionnel et environnemental reconnue par les Ministères de l’Agriculture et de la Santé.Bleu-Blanc-Coeur is an organization created to improve the nutritional and environmental quality of our diet leading to a new responsible agriculture. The basic idea of Bleu-Blanc-Coeur is “to feed people well, we must first take care of our crops and the health of our animals”. The association brings farmers, companies, practitioners, scientists and consumers together. Bleu-Blanc-Coeur manages specification guidelines that impose a double obligation of means and results which describe improved nutritional qualities of food related with feeding and breeding practices. The Bleu-Blanc-Coeur approach is based on a strong scientific background of 320 publications and 5 clinical trials. These scientific data have demonstrated the value of these farming practices for animal and human health and also for the environment. Bleu-Blanc-Coeur is an approach of nutritional and environmental interest recognized by Authorities such as the French Ministries of Agriculture and Health

Un nouveau clone et une nouvelle méthode pour la production et la purification de l’entérotoxine STb d’Escherichia coli

Le gène de l’entérotoxine thermostable b (estB) d’Escherichia coli a été fusionné au gène de la protéine liant le maltose (malE) dans le vecteur pMAL-p via PCR. Par la suite, deux constructions plasmidiques ont été realisées à partir de ce nouveau vecteur, nommé pMAL-STb. Dans un premier temps, un marqueur hexahistidine (His6) a été ajouté entre malE et estB, et dans un deuxième temps, un marqueur décahistidine (His10) a été placé en amont de malE. La séquence signal de la protéine liant le maltose (MBP) dirige l’exportation de la protéine de fusion du cytoplasme vers le périplasme, où l’entérotoxine STb acquière sa conformation active. MBP est également reconnue pour améliorer le rendement et la solubilité de la protéine passagère tandis que le marqueur histidine, connu comme étant le meilleur marqueur d’affinité pour la purification protéique, facilite sa purification jusqu’à homogénéité. De plus, les gènes fusionnés sont sous le contrôle du promoteur tac (Ptac), un promoteur fort et inductible. Suite à l’induction par l’IPTG, la souche recombinante exprime une protéine d’environ 48 kDa, qui est facilement identifiable par électrophorèse à partir du surnageant obtenu via choc osmotique. Une séquence encodant un site de clivage spécifique au facteur Xa est présente dans le plasmide afin de séparer les marqueurs MBP et histidine de STb. Le clivage de la protéine de fusion avec le facteur Xa libère MBP (42 kDa) attachée au marqueur histidine et un polypeptide de 5.2 kDa, correspondant au poids moléculaire de STb mature. Avec cette méthode, nous visons à obtenir une méthode plus efficace pour la production et la purification de STb.The heat-stable enterotoxin b gene (estB) of Escherichia coli was fused to the gene for maltose-binding protein (malE) into the pMAL-p vector using PCR. Afterward, two plasmid constructs were realized from this new vector, named pMAL-STb. Firstly, a hexahistidine tag (His6) was added between malE and estB and secondly, a decahistidine tag (His10) was placed upstream of malE. The signal sequence of maltose-binding protein (MBP) directs the export of the fusion protein from the cytoplasm to the periplasm, where the enterotoxin STb acquires its active conformation. MBP is also known to improve the yield and solubility of the passenger protein while the histidine tag, viewed as the best affinity tag for protein purification, facilitates its purification to homogeneity. Furthermore, the fused genes are controlled by the tac promoter (Ptac), a strong inducible promoter. Following IPTG induction, the recombinant strain expressed a protein of approximately 48 kDa, which is easily identified from osmotic shock fluid following electrophoresis. A sequence encoding a factor Xa cleavage site is present in the plasmid to separate MBP and histidine tags from STb. The cleavage of the fusion protein with factor Xa generates the maltose-binding protein (42 kDa) attached to the histidine tag and a polypeptide of 5.2 kDa, corresponding to the molecular mass of mature STb. With this method, we aim at obtaining a more efficient way to produce and purify STb