Gas-filled Liposomes Essay Example | Topics and Well Written Essays - 750 words

Gas-filled Liposomes - Essay Example In medicine, MRI is an invaluable tool for soft tissue assessment as it analyses the absorption and transmission of high frequency radio waves absorbed by water in high magnetic fields to derive cross-sectional images of soft tissue (Alexander et al, 1996; Maresca et al, 1998). The use of GFLs as components of tracer materials may enhance the use of this technology in medical diagnostics (Klibanov, 1999). A recently developed method of GFL preparation (Vangala et al, 2007) involves the homogenization of 1,2-dipalmitoyl-sn-glycero3-phosphorocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphorocholine DSPC in aqueous medium below their transition temperatures to effect a stable GFL formation. Biophysical assessment indicated that the initial vesicle size was 10microm, which increased to approximately 12 microm for DPPC and 23 microm for DSPC containing vesicles in 7 days at 25C. The addition of cholesterol 1: 0.5 or 1:1 to the DPPC lipid homogenate produced significant increases in vesicle size as well as enhanced stability compared to DPPC alone (Liu et al, 2000). Surface charge induction was implemented by the addition of stearylamine at a molar ratio of 0.125 or 0.25. The surfactant did not appear to be incorporated into the bilayer. Microscopic analyses demonstrated that spherical structures ranging from 1-8 microm were produced by this method. When used as cardiographic contrast agents in cardiac assessment in experimental animals, GFL performed with greater sensitivity than aqueous liposomes (Mohammed et al, 2004; Unger et al, 1992, 1993). 2-Aim and Objective The objective of this research is to prepare Gas-filled liposomes (GFL) and to characterize their biophysical properties. The goal is to prepare liposomes that are gas-filled (air) using experimental lipid components and to assess their stability and biophysical properties. This assessment may facilitate the use of GFL for both medicinal purposes in MRI and in environmental studies such as novel methods for oil recovery. 3-Materials Sigma-Aldrich (Poole, Dorset, UK) 1,2-dimysteroyl-sn-glycero-3-phosphorocholine DMPC(C14) 1,2-dipalmitoyl-sn-glycero-3-phosphorocholone DPPC (C16) 1,2-distearoyl-sn-glycero-3-phosphorylcholine DSPC (C18) methyl cellulose cholesterol stearylamine phosphate buffered saline tablets Lipid Products (Nutfield, Surrey, UK) egg-phosphatidylcholine (PC) double-distilled water 4-Methods Gas-filled liposome preparation: GFL will be prepared using a modified method first developed by Unger (1999). This method involves the following steps: 1. 50 mg of DSPC or other lipid added to 5ml of doubly-distilled water in a 50ml beaker to hydrate the lipid. Cholesterol or stearylamine should be added if these components are to be included in the vesicle preparation. 2. Mixture is homogenized for 4 minutes below the phase transition temperature of the lipid using a high speed homogeniser (Ultra -Turrax T8). 3. A gas (air) filled lipid layer will form above the aqueous layer following homogenization: this constitutes the GFL fraction. 4. Varying GFL concentrations will be prepared by mixing varying volumes

History of the Middle East Research Paper Example | Topics and Well Written Essays - 3000 words

History of the Middle East - Research Paper Example The increased developments in Middle East had been pronounced since early decades, and can be traced back in the second half of 1500s when Ottoman Empire started expanding its domain (Fischbach 2013, 56). From inception, Islam had shaped politics in regions where it dominated, especially in Middle East. Despite the fragmentation of the political authority in Muslim land, Islam continued to be powerful and had a strong political solidarity bond. Collapse of Ottoman Empire facilitated the entry of Europeans in Middle East who aimed at colonizing them. British domination of local politics remained effective until early 1970s. Emergence of independent and sovereign states between 1940s and 1050s altered traditional foundations and domestic power equations in state-society relations. The modern states were unprepared for any competitive international environment and offer substantial support to the growing nationalist aspirations. Such aspirations appeared in response to political develop ments and Palestinian-Israeli conflicts that served as the catalyst for regional instability and conflict. This led to the political environment in 20th century characterized by political turmoil, extremism and conquests. Therefore, this paper investigates why the creation of the state of Israel failed to solve the Jewish problems (Gettleman 2012, 145). Creation of state of Israel The creation of state of Israel was predicated on the constitution of Jews as people of special identity and placed the nation on specific territory, as well as the juridical and territorial independence of the nation in modern country. The formation of state of Israel was enhanced by Zionism and deliberated by articulation from individuals who set to revive the ancient kingdom in a modern approach. This called for territorial and political independence for it to be successful. Soon after the end of World War II, the British evacuated Palestine and recommended partitioning of the Palestine into two states. Arabs rejected while Jewish accepted, though they advocated that they be given more than 55 percent of the land. This facilitated the War of control during which Israel declared its statehood in 1948. Such victory over the Arabs facilitated an influx of Jewish refugees from Europe and other Muslim word and outflow of fleeing Arab Palestinians (Klieman 1990, 63) One year after the partition plan by the general assembly, the resolution 94 was issued to offer right of return of the Arabs to the post-mandate Palestine. However, UN possessed no powers to enforce such resolutions since Israel was determined to prohibit Arabs to return to their homes after fleeing. Such unresolved problems remain the major source of conflicts for quite some time. In 1950, Israel’s parliament passed the law of return (Gettleman 2012, 148). Partition Plan Most states in UN General Assembly voted in the partition plan for the Palestine in 1947. Such a resolution called for the termination of the manda te by Britons and created two states; one for Arabs and the other one for Jews. City of Jerusalem was entitled to the enjoyment of special status under the international administration. The resolution was voted in by thirty one countries while seven voted against the resolution. Zionists accepted the resolution while Arabs opposed it since it advocated for a single state dominated by Arab majority. Traditionally, the twin objectives of the foreign policy in Israel of