Development of Methodology for the Measurement of Prostacyclin and Thromboxane Production: Possible Relevance of Prostacyclin/Thromboxane Balance in Clinical Conditions

This thesis describes the historical development of our knowledge of prostaglandins and thromboxane and the synthesis, metabolism and actions of prostacyclin and thromboxane. Chapter 3 then presents work on the development and validation of a radioimmunoassay to measure plasma prostacyclin metabolite levels. Comparisons are made of results using a tritiated and an iodinated radioactive label and also of results obtained using different antibodies. Results are also presented of an assay to measure prostacyclin stimulating factor in normal plasma and serum. A method developed to measure endothelial cell prostacyclin production using a human umbilical artery perfusion model is described. Chapter 4 describes the various methods which may be used to measure production of thromboxane A2. Firstly a radioimmunoassay is described which measures thromboxane B2 the stable metabolite of thromboxane A2 and results using this assay for both plasma and serum samples are produced. Methods for measuring thromboxane generation by platelets in response to aggregation with 4 ug/ml of collagen and also serum thromboxane B2 levels in bleeding time blood are described. The second part of the thesis is concerned with an attempt to validate the relevance of the prostacyclin/thromboxane balance in clinical situations. Possible ways of altering the thromboxane/prostacyclin balance which may have clinical implications were explored. Plasma levels of prostacyclin metabolites and thromboxane before and after ingestion of drugs known to alter arachidonic acid metabolism are shown. Studies on the effect of dietary fat intake and smoking on the prostacyclin/thromboxane balance are presented. Chapters 6 and 7 examine the thromboxane/prostacyclin balance in a range of vascular diseases and in bleeding disorders respectively. A Chapter is then devoted to the possible relevance of the thromboxane/prostacyclin balance in pregnancy and associated disorders of pregnancy. Chapter 9 summarises the results of this work and also discusses the implications for future research

Recent perspectives on trade and inequality

The 1990's dealt a blow to traditional Heckscher-Ohlin analysis of the relationship between trade and income inequality, as it became clear that rising inequality in low-income countries and other features of the data were inconsistent with that model. As a result, economists moved away from trade as a plausible explanation for rising income inequality. In recent years, however, a number of new mechanisms have been explored through which trade can affect(and usually increase) income inequality. These include within-industry effects due to heterogeneous?firms; effects of offshoring of tasks; effects on incomplete contracting; and effects of labor-market frictions. A number these mechanisms have received substantial empirical support.Labor Markets,Economic Theory&Research,Labor Policies,Trade Policy,Emerging Markets

Waterfowl Populations in Eastern Lancaster Sound and Western Baffin Bay

The seasonal distributions of oldsquaws (Clangula hyemalis), common eiders (Somateria mollissima) and king eiders (S. spectabilis) were determined through aerial surveys in eastern Lancaster Sound (1976, 1978 and 1979) and northwest Baffin Bay (1978, 1979). Sightings of geese are summarized in an Appendix. The major spring influx of both eiders occurs about the second week of May but most oldsquaws do not arrive until the first half of June. In spring, all three species are rare in offshore areas, are most abundant along coasts in the northern half of the study area, and tend to depart to nesting areas during the last week of June. Oldsqaws molt along coasts of Lancaster Sound and northwest Baffin Bay, but both species of eiders undertake molt migrations. Three waves of eider out-migration were detected in 1976 and 1978. Distribution and movements within the study area are related to probable migrations routes and ice conditions.Key words: oldsquaw, king eider, common eider, geese, aerial surveys, distribution, molt migration, eastern Arctic, Baffin Bay, Lancaster Soun

Recent findings on trade and inequality:

The 1990's dealt a blow to traditional Heckscher-Ohlin analysis of the relationship between trade and income inequality, as it became clear that rising inequality in low- income countries and other features of the data were inconsistent with that model. As a result, economists moved away from trade as a plausible explanation for rising income inequality. In recent years, however, a number of new mechanisms have been explored through which trade can affect (and usually increase) income inequality. These include within-industry effects due to heterogeneous firms; effects of offshoring of tasks; effects on incomplete contracting; and effects of labor-market frictions. A number of these mechanisms have received substantial empirical support.trade inequality,

The Reactions of Muskoxen to Snowmobile Harassment

Twenty-one harassment trials on 14 muskox herds were conducted in April and May 1982 on eastern Melville Island, N.W.T. Each trial consisted of a slow approach directly toward the herd on a snowmobile. The snowmobile, returned along its approach path as soon as 50% of the herd was alerted. Distance at which the first animal reacted (IRD) averaged 345.0 m(range 162-650 m) and the distance from the herd at closest approach (CAD) averaged 267.2 m(range 87-645 m). IRD was positively correlated with wind speed. No correlation between CAD and any of the measured variables was found. Maximum reaction level of the herd was positively correlated with herd size (rs = 0.488, P<0.05). No significant differences in IRD or CAD were found between or among classes of discrete variables such as topography and wind direction, but sample sizes were small. Adult female muskoxen reacted first more frequently than expected (P<0.02). Two herds were approached repeatedly (one six times and one three times) to assess habituation. Results were inconclusive. IRD for the herd that was approached three times decreased progressively. IRD for a herd approached six times was variable but shortest on the sixth approach and the reaction level of the herd also was low on the sixth approach..Key words: muskoxen, harassment, snowmobile, Melville Island, N.W.T.Mots clés: boeuf musqué, harcèlement, motoneige, île Melville, T.N.-O

Effects of Snow and Ice on Waterfowl Distribution in the Central Canadian Arctic Islands

Aerial surveys were conducted in 1974 and 1975 to determine distribution and abundance of waterfowl along the coasts of Somerset, Cornwallis, Little Cornwallis, and Byam Martin islands, Boothia Peninsula, as well as parts of Prince of Wales, Devon, Bathurst, and Melville islands. Waterfowl nested normally in 1975 but were prevented from doing so in 1974 by a late thaw. In 1974, but not in 1975, Barrow Strait was ice free by 1 June. Densities of most species were lower in spring 1975 than in 1974, when inhospitable conditions inland forced the birds to concentrate in coastal areas. In late summer Brant (Branta bernicla) and Oldsquaw (Clangula hyemalis) were more numerous in 1975 than in 1974; Brant left the central High Arctic in midsummer 1974, but the reason for the smaller number of Oldsquaw is not evident. Both Snow Geese (Chen caerulescens) and eiders (Somateria spp.) were more abundant in late summer 1974 than in 1975. Many Snow Geese moved to southeastern Somerset Island and adjacent waters to moult in 1974. In 1975 many eiders and Snow Geese remained at inland locations with their broods. Queens Channel, northern Somerset Island and Bellot Strait were particularly important to waterfowl, irrespective of spring phenology. Melville and Byam Martin islands were used by Brant, and Canada Geese (Branta canadensis) occurred mainly on the Boothia Peninsula. Snow Geese were abundant in both years in southeastern Somerset Island, particularly near Creswell Bay, where both breeding and moulting occurred. Coastal waters of Barrow Strait, Prince Regent Inlet and the Gulf of Boothia were heavily used by Oldsquaw in spring and summer, and Crooked Lake, Prince of Wales Island, was used by many moulting Oldsquaw in both years. Common Eiders (S. mollissima) occurred principally in Queens Channel, Barrow Strait and near Bellot Strait; King Eiders (S. spectabilis) also concentrated in the same areas but were more widely distributed throughout the study area.Key words: Arctic Islands, N.W.T., waterfowl distribution, nonbreeding, aerial surveys, Brant, snow Geese, Oldsquaw, eidersMots clés: îles arctiques, T. N-O., distribution des oiseaux marins, non-accouplement, inventaires aériens, bernache cravant, oie blanche, canard à longue queue, eide

Recent Findings on Trade and Inequality

The 1990’s dealt a blow to traditional Heckscher-Ohlin analysis of the relationship between trade and income inequality, as it became clear that rising inequality in low- income countries and other features of the data were inconsistent with that model. As a result, economists moved away from trade as a plausible explanation for rising income inequality. In recent years, however, a number of new mechanisms have been explored through which trade can affect (and usually increase) income inequality. These include within-industry effects due to heterogeneous firms; effects of offshoring of tasks; effects on incomplete contracting; and effects of labor-market frictions. A number of these mechanisms have received substantial empirical support.