Proteomic Comparison of Entamoeba histolytica and Entamoeba dispar and the Role of E. histolytica Alcohol Dehydrogenase 3 in Virulence

The protozoan intestinal parasite Entamoeba histolytica infects millions of people worldwide and is capable of causing amebic dysentery and amebic liver abscess. The closely related species Entamoeba dispar colonizes many more individuals, but this organism does not induce disease. To identify molecular differences between these two organisms that may account for their differential ability to cause disease in humans, we used two-dimensional gel-based (DIGE) proteomic analysis to compare whole cell lysates of E. histolytica and E. dispar. We observed 141 spots expressed at a substantially (>5-fold) higher level in E. histolytica HM-1∶IMSS than E. dispar and 189 spots showing the opposite pattern. Strikingly, 3 of 4 proteins consistently identified as different at a greater than 5-fold level between E. histolytica HM-1∶IMSS and E. dispar were identical to proteins recently identified as differentially expressed between E. histolytica HM-1∶IMSS and the reduced virulence strain E. histolytica Rahman. One of these was E. histolytica alcohol dehydrogenase 3 (EhADH3). We found that E. histolytica possesses a higher level of NADP-dependent alcohol dehydrogenase activity than E. dispar and that some EhADH3 can be localized to the surface of E. histolytica. Episomal overexpression of EhADH3 in E. histolytica trophozoites resulted in only subtle phenotypic differences in E. histolytica virulence in animal models of amebic colitis and amebic liver abscess, making it difficult to directly link EhADH3 levels to virulence differences between E. histolytica and less-pathogenic Entamoeba

Motion Picture Distribution, Film Splitting, and Antitrust Policy

The United States Department of Justice (DOJ) launched a major program in the mid-1980s against film splitting agreements, whereby motion picture exhibitors in a city agree not to competitively bid for movies. The DOJ held such agreements are per se price fixing conspiracies. This Article examines film splitting and its per se status. The author examines previous explanations for film splitting by reviewing the history of movie distribution and the efficiencies of distribution practices prior to the famous Paramount decision. The author also compares alternative methods of licensing and concludes that film splitting can reduce distribution costs, increase the number of films shown relative to competitive bidding for films, and help maintain lower box office prices. The author further concludes splitting agreements were an attempt to preserve distribution efficiencies eliminated under the Paramount rulings. Moreover, splitting should have been analyzed under a rule of reason

Motion Picture Distribution, Film Splitting, and Antitrust Policy

The United States Department of Justice (DOJ) launched a major program in the mid-1980s against film splitting agreements, whereby motion picture exhibitors in a city agree not to competitively bid for movies. The DOJ held such agreements are per se price fixing conspiracies. This Article examines film splitting and its per se status. The author examines previous explanations for film splitting by reviewing the history of movie distribution and the efficiencies of distribution practices prior to the famous Paramount decision. The author also compares alternative methods of licensing and concludes that film splitting can reduce distribution costs, increase the number of films shown relative to competitive bidding for films, and help maintain lower box office prices. The author further concludes splitting agreements were an attempt to preserve distribution efficiencies eliminated under the Paramount rulings. Moreover, splitting should have been analyzed under a rule of reason

Resale Price Maintenance: Output Increasing or Restricting? The Case of Distilled Spirits in the United States.

Theories of resale price maintenance (RPM) differ strongly on the pro- and a nti-competitive effects on RPM. There are few tests of the welfare ga ins or losses from RPM in industry case studies. This paper tests RPM 's welfare effects in the retail sale of distilled spirits in the U.S Using regression analysis to estimate demand, comparing liquor stor e license values over time, and analyzing political contributions, th e study finds that efficiency arguments for RPM are unsupported, with RPM leading to a reduction in distilled spirits consumption. Evidenc e shows substantial wealth transfers from consumers to retail liquor store owners due to RPM. Copyright 1987 by Blackwell Publishing Ltd.

The economics of advertising: Where's the data?

Advertising, product differentiation, manufacturing industries,