Hydrolysis of lac resin yields a mixture of acids among which only two - aleuritic (up to 40%) and shellolio (up to 5%) - have been adequately characterised and examined by several investigators. The work embodied in this thesis represents some studies of the aliphatic acids in lac hydrolysate. The presence of a range of non-hydroxy acids (1.1%) 6-hydroxytetra- decanoic acid (not less than 8%), l6~hydroxyhexadecanoic acid and snother monohydroxyhexadecanoic acid has been demonstrated. The 6-hydroxytetradecanoic acid has been shown to be identical with butolic acid recently isolated by chemists of the Indian Lac Research Institute but considered by them to be a C1B hydroxy acid. The other acids have not previously been reported as constituents of lac resin. Reversed-phase chromatography was found to be unsuitable for the examination of lac acids, probably due to their highly hydroxylated nature. Dehydroxylation experiments on lac acids by lodlnatlon- deiodination and by bromination-debrominatlon revealed the presence of hydroxylated tetradecanoic and hexadecanoic acids; brominatlon- debrominatlon reactions also showed the presence of small amounts of vicinal dihydroxy acids of these two series. Partition of lac acids between petroleum ether and 80% aqueous methanol and subsequent examination of the petroleum other-soluble material (1.1%) revealed the presence of dodecanoic (trace). tetradec-9-onoic and tetradecanoic acids (25%), hexadec-9-enoic acid (13%), hexadecanoic acid (53%), octadec-9-enoic acid (7%) and octadecanoic acid (2%). Examination of lac acids by adsorption, gas-liquid and thin layer chromatography showed the presence of 6-hydroxy-tetradecanoic acid (8% or more of lac acids), 16-hydroxy-hexadeoanoic acid and another monohydroxyhexadeoanoic acid.

The opening pages of this section are devoted to a review of the evidence revealed by the various experiment al techniques which have been applied to the problem. The relationships between the several products and their variations with temperature and pressure have been illustrated graphically and the significance of thane change discussed. The lack of stoichiometric balance is also considered and some possible explanations proposed. This is followed by an outline of the various mechanisms which are available for the production of the resultants in the observed quantities, and the relative merits of these are discussed. On the basis of this discussion a value is proposed for the dissociation energy of the central c-c bond. The final section is concerned with the conclusions which can be drawn from this value regarding the energies involved in other steps of the reaction and their significance in the general scheme of bond energies.

The prevailing viewpoint on the history of childhood is that: (a) there was no concept of childhood prior to the 17th century; (b) children were cruelly disciplined; (c) there was a formal parent-child relationship. The evidence presented to support the thesis is suspect and there is little systematic analysis of any source. Moreover, the thesis is not universally accepted - other authors have shown that there was a concept of childhood in the middle ages. In addition, the main writers have concentrated on discipline, to the virtual exclusion of all other childhood experiences. This study, covering the period from the 16th to the 19th century inclusive, has attempted to provide a detailed analysis of primary sources of evidence (autobiographies and diaries) in order to reconstruct child life in the past. Newspaper reports on child abuse cases occurring before the prevention of cruelty to children act in 1009 have also been examined. The methodological problems inherent in the sources used have been considered. The information provided by the texts suggests that parents did possess a concept of childhood, were not indifferent to their children and did not treat the latter cruelly. (With reference to the last point, the newspaper reports also reveal that child abuse was condemned before specific child protection legislation appeared). Although there was discord between parents and adolescent offspring, in the vast majority of families there was an affectionate parent-child relationship. Parents did not totally control their children's lives. Moreover, the texts suggest that the basics of child life have changed very little. Children did pass through such developmental stages as teething and talking at a similar age to modern children, although the texts do disclose the considerable amount of individual variation. Children played and also received at least some education in every century studied. Nonetheless there have been some changes in parental care and child life, as revealed in the texts: the concept of the innocence of childhood did not appear till the 10th century; there was an increase in thinking about the nature of childhood and the parental role in the abstract; there was a lessening of parental control in such areas as career and marriage through the centuries and there was an increase in the severity of the discipline meted out to children in the early 19th century.

Weapons are acquired to protect the national security interests of the state: they may be used to settle disputes between one state and another, or they are accumulated as a defensive precaution to dissuade any future or offensive military action. Quite often, weapons are used in great quantities in various internal conflicts to the detriment of the individual, both civilian and combatant. Over time, the international community has developed certain humanitarian principles, norms, treaties and control mechanisms to reduce tensions between states, and to lessen the consequences of unrestrained weapons use. International Humanitarian Law (IHL) or the Law of War seeks to regulate or prohibit the use of particular weapons based on the principle that the means of injuring one's enemies are not unlimited, and that there should be restraints on weapons which are indiscriminate or cause unnecessary suffering. Arms control and disarmament law seeks to limit or even prohibit the use, transfer or trade, production, and stockpiling of certain weapons. There is an interplay between these two approaches when the weapon in question is being restrained because of its perceived nature. Two weapons that have evoked calls for prohibition or restriction because of their pernicious nature are chemical weapons and land mines. Currently, in the Post-Cold War security environment, both these weapons are high on the international political and security agenda rendering them relevant subjects for a comparative study. This thesis examines the respective histories of these regimes of restraint and attempts to determine what lessons may be drawn in comparing efforts to place legal prohibitions on so-deemed inhumane or intolerable weapons. By examining the main similarities and differences in responses to chemical weapons and land mines, it may possible to understand what criteria are necessary for prohibiting a weapon on humanitarian grounds.

A wide range of [1-14C] monoenoic (32) and polyenoic (8) fatty acids and two unlabelled fatty acids containing a 6,7-cyclopropene ring were prepared by existing methods. Several procedures for the conversion of oleic acid to its C17 iodide with concomitant decarboxylation were investigated without success. The CMR spectra of (27) saturated, (65) cis and trans monoenoic, (39) monoynoic, (2) cyclopropene, (20) cis-polyenoic, (14) diynoic and (10) mixed-function diunsaturated acids and methyl esters were recorded and interpreted. An empirical approach, based on the shielding and deshielding influence of functional groups on the rest of the molecule, was employed, and the assignment of 13C resonances by this method agreed with those obtained by other researchers using different methods. The shielding and deshielding effects were generally additive, except when two function groups were close together. CMR spectroscopy can be used to distinguish cis and trans olefins, locate double and triple bond positions and interpret patterns of polyunsaturation. The specificity of the mammalian desaturases was examined by incubating [1-14C] fatty acids with a rat liver microsomal preparation and analysing the products formed after one hour. The Delta9 desaturase was believed to hold its substrate by the binding of the CoA moiety at the carboxyl end and by the fit of the alkyl chain into a deep, narrow cleft, where, except at the active centre, it was constrained to take up predominantly trans conformations. This model is confirmed. Trans monoenoic acids were generally Delta9 desaturated to give as high conversions as saturated acids, and the Delta7t and Delta11t monoenoic acids gave the corresponding Delta7t9c and Delta9c11t conjugated dienes. Cis monoenoic acids, which were not expected to fit into the enzyme cleft between C(5) and C(15), were not Delta9 desaturated unless the double bond position was beyond Delta13, and even then they were much poorer substrates than stearic acid. The Delta6 desaturase shows a much wider substrate specificity than was previously anticipated. The enzyme can accommodate a wide range of substrate chain lengths (at least C14 to C22) and the Delta9 cis double bond is not obligatory for Delta6 desaturation. The model advanced for the enzyme contains two distinct features. Firstly, a region of steric constraint between C(10) and C(13) on the substrate geometry acceptable to the enzyme is proposed. Secondly, pi-bond binding sites on the enzyme surface in the C(9) to C(13) region are envisaged. Dienoic acids with a Delta9c double bond and adjacent olefinic unsaturation (Delta11- Delta13) were much better substrates than monoenoic acids or dienoic acids containing a Delta9c double bond and a second double bond beyond the Delta13 position. Therefore, to bed substrate for Delta6 desaturation the co-operative binding of two ands, separated by 0-2 methylene groups, to these Delta-binding is essential. The Delta5 desaturase also shows a wider substrate specificity than was previously anticipated. The principal feature is a high degree of chain length specificity. Within the C16-C20 range tested C20 was the optimum chain length while minimal Delta5 desaturation occurred when the chain length dropped to C16. A region of steric constraint between C(10) and C(13) on the substrate geometry acceptable to the enzyme is envisaged. However, the range of acids tested was not extensive and an evaluation of the role of Delta-bonds in substrate-enzyme binding was not possible. No Delta4 des1aturation was observed. This agreed with other studies.

No description available.

The evolutionary status of the hot R CrB stars has long remained a matter of conjecture, primarily because of the relative dearth of relevant observational material. Previously the group had been thought to occupy a position intermediate in status between the EHe and R CrB classes as they have (at least at first glance) observational properties in common with both types of object. The photosphere of DY Cen has been quantitatively confirmed to be hydrogen-deficient and photometric variations suggest the star undergoes short period pulsations. Using a period-temperature relation applicable to hydrogen-deficient stars it would appear that this object has similar physical properties to both the EHe and R CrB stars. Narrow band imaging of V348 Sgr has shown that the associated nebula exhibits a bipolar structure and therefore must be closely related to planetary nebulae rather than H II regions. Spectroscopic observations have proved that the star in its present evolutionary state is incapable of ionising the nebula. Several scenarios for this behaviour are briefly discussed. The large helium enrichment found in the nebula indicates that processed material must have been ejected during the last major episode of mass loss. Evidence is presented that suggests a strong hydrogen abundance gradient exists within the nebula. A novel technique has been developed for determining reddening distances. Its main advantage over other similar methods is that both early and late-type stars may be used to establish the reddening-distance relationship. With more development this technique may prove to be an important tool in distance determinations for objects such as planetary nebulae etc. This technique was used to derive a distance of (4. 7±1.0) kpc for V348 Sgr. Using the core-mass relation for hydrogen-deficient stars implies that both V348 Sgr and MV Sgr are lower mass and luminosity objects than EHe and R CrB stars. The evidence presented in this thesis indicates that the hot R CrB group is not a homogeneous one. DY Cen is much more luminous and massive than the other members. The mass and luminosity of V348 Sgr and MV Sgr are consistent with the scenario that both have recently suffered a thermal pulse (causing re-ignition of a helium burning shell) and are currently looping back to the R CrB domain of the H R diagram.

Master of Science

Infection with the hepatitis C virus (HCV) has a big impact on global health. It is estimated that approximately 3 % of the world’s population carry HCV, putting more than 200 million people at risk of developing severe liver disease, including chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. The HCV encoded viroporin p7 forms ion channels that are crucial for the assembly and secretion of infectious viruses, making it a potential drug target. Its hydrophobic nature makes p7 notoriously difficult to investigate in an untagged native form. A previously determined 16 Å electron microscopy single-particle reconstruction in detergent showed a hexameric, flower-shaped p7 protein. In conjunction with one hexameric and several monomeric p7 solution state NMR structures published, this constitutes the currently available structural information framework. An E. coli expression system is introduced, which is especially adapted to express isotopically labeled p7. For the first time, suitable solution-state NMR conditions at physiological pH and temperature were identified that gave rise to high quality spectra suitable to interrogate iminosugar drug interactions with untagged isotopically labeled J4 p7 (C27S) solubilised in detergent. A novel secondary structure topology was observed and preliminary iminosugar binding sites were determined. Further, a DIB (droplet interface bilayer) system to analyse p7 ion channel function was established, which is suitable to elucidate how inhibitors act on p7 genotypes and how different lipids influence the ion channel function of p7. The p7 oligomeric state was further investigated using native gel analysis, showing that isolates representing HCV genotypes 1 - 6 form oligomeric complexes. An ion channel defective dibasic mutant implicated in severely compromising viral fitness is also shown for the first time to form an oligomer, implicating that it is not an assembly problem that leads to the abrogated function.

Le virus de l'hépatite C (VHC) est une cause majeure d'affection hépatique chronique, notamment la cirrhose et le cancer du foie. On estime que 170 millions de personnes dans le monde sont des porteurs chroniques du VHC et que 3 à 4 millions de personnes sont infectées chaque année. Un des handicaps majeurs de la recherche sur le VHC est l'absence de systèmes de culture in vitro efficaces et de modèles animaux. Nous avons ainsi choisi une approche recombinante pour l'étude de protéines E1, E2 et p7 du VHC.Les protéines E1, E2 et p7 qui sont impliquées dans des étapes essentielles du cycle viral sont des protéines membranaires. Cependant, l'expression recombinante de cette classe de protéine est extrêmement complexe. En effet, la surexpression des protéines membranaires est souvent toxique pour les cellules hôtes. Ce phénomène est provoqué par l'agrégation ou la dégradation des protéines dans le cytoplasme dû à un manque de membrane disponible pour assurer leur intégration sur la cellule hôte. De plus, la surexpression de protéines membranaires induit la saturation de la machinerie cellulaire liée aux protéines membranaires. Ce détournement empêche le déroulement d'un cycle cellulaire normal et est ainsi fatal pour la cellule hôte. La forte concentration de protéines membranaires ou encore le fait que celles-ci soient hétérologues peut également provoquer la déstabilisation de la membrane de la cellule hôte et de son homéostasie. Afin de nous affranchir de ces limitations, nous avons utilisé une méthode de production des protéines membranaires sous forme native par un système acellulaire en présence de liposomes ; une technologie brevetée par l'université Joseph Fourier et exploitée par la société Synthelis. Dans un premier temps, nous avons procédé à la mise en place du système de production exploitant un lysat bactérien d'E. coli et d'un mélange énergétique complémentaire. Nous avons ensuite utilisé ce system pour étudier la viroporine p7. Cette protéine est essentielle pour la production de particules virales infectieuses et est impliquée dans l'assemblage viral ce qui en fait une cible thérapeutique intéressante. La production de protéoliposomes p7 en grande quantité nous a permis la caractérisation de la protéine par des techniques biochimiques et biophysiques. Nous avons mis en évidence l'inhibition de l'oligomérisation de p7 par le HMA qui ainsi inhibe sa fonction canal ionique. Grâce à la flexibilité du système d'expression acellulaire nous avons caractérisé la structure de la viroporine dans la membrane par réflectivité de neutron et avons confirmé la forme en entonnoir du complexe protéique. Des résultats préliminaires sur les proéoliposomes E1E2 quant à eux permettent d'espérer la production prochaine de particules virales mimant le VHC afin de mieux l'étudier et de lutter contre cette épidémie.L'ensemble de ces résultats confirment la pertinence de l'expression de protéines membranaires sous formes natives en système acellulaire en présence de liposomes. Les protéoliposomes produits constituent des nouveaux outils pour l'étude du VHC et permettent d'envisager de très grandes applications thérapeutiques ainsi que le développement de biomédicaments basés sur l'utilisation de protéines membranaires recombinantes. / The Hepatitis C virus (HCV) is a major cause of chronic liver disease, including cirrhosis and liver cancer. An estimated 170 million people worldwide are chronically infected with HCV and 3 to 4 million people are infected each year. One of the major handicaps of the HCV research is the lack of effective in vitro culture systems and animal models. To adress this issue, we chose a recombinant approach to study the E1, E2 and p7 proteins of HCV.The E1, E2 and p7 proteins are involved in critical steps of the viral cycle. They are membrane proteins, a class of protein that is extremely complex to express. Indeed, overexpression of membrane proteins is often toxic to the host cells. This phenomenon is caused by protein aggregation or degradation in the cytoplasm due to a lack of available membrane space for their integration into the host cell. Moreover, overexpression of membrane proteins induces saturation of the cellular machinery linked to membrane proteins. This diversion prevents the flow of a normal cell cycle and is fatal to the host cell. Destabilization of the host cell's membrane and its homeostatis may also be caused by the high concentration of membrane proteins or their heterologous nature. To circumvent these limitations, we used a method for producing membrane proteins in their native form by a cell-free system in the presence of liposomes; a technology patented by the University Joseph Fourier and licenced by the startup company Synthelis. First, we have set up the cell-free production system using a bacterial lysate from E. coli and a complementary energy mix. We then used this system to study the p7 viroporine. This protein is essential for the production of infectious virus particles and is involved in viral assembly making it an attractive therapeutic target. The production of a large quantity of p7 proteoliposomes allowed us to characterize the protein by biochemical and biophysical techniques. We have demonstrated the inhibition of oligomerization of p7 by HMA, which thereby inhibits its ion channel function. Thanks to the flexibility of the cell-free expression system we have characterized the structure of the viroporine within the membrane in a neutron reflectivity assay and have confirmed the funnel shape of the protein complex. Preliminary results on proteoliposomes E1E2 offer hope for the production viral particles mimicking the hepatitis C virus in order to better study the virus and fight against this epidemic.Together, these results confirm the suitability of the expression of membrane proteins in native forms using a cell-free system in the presence of liposomes. Proteoliposomes products are a new tool for the study of HCV and consideration for very broad therapeutic applications and the development of biopharmaceuticals based on the use of recombinant membrane proteins.