The Clostridial neurotoxins, botulinum and tetanus, gain entry into neuronal cells by protein recognition involving cell specific binding sites. The sialic or N-acetylneuraminic acid (NeuAc) residues of gangliosides attached to the surface of motor neurons are the suspected recognition and interaction points with Clostridial neurotoxins, although not necessarily the only ones. We have used electrospray ionization mass spectrometry (ESIMS) to examine formation of complexes between the tetanus toxin C fragment, or targeting domain, and carbohydrates containing NeuAc groups to determine how NeuAc residues contribute to ganglioside binding. ESI-MS was used to rapidly and efficiently measure dissociation constants for a number of related NeuAc-containing carbohydrates and NeuAc oligomers, information that has helped identify the structural features of gangliosides that determine their binding to tetanus toxin. The strength of the interactions between the C fragment and (NeuAc){sub n}, are consistent with the topography of the targeting domain of tetanus toxin and the nature of its carbohydrate binding sites. The results suggest that the targeting domain of tetanus toxin contains two binding sites that can accommodate NeuAc (or a dimer). This study also shows that NeuAc must play an important role in ganglioside binding and molecular recognition, a process critical for normal cell …

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of the third year of a 42 month research program that is aimed at an understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work focused on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A mathematical model that describes uptake and crosslinking reactions as a function of time was derived. The model was probability based and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. A liquid chromatography apparatus to experimentally measure the size and molecular weight distributions of polymer samples was developed. The method worked well for polymer samples without the chromium crosslinker. Sample retention observed during measurements of gelant samples during the gelation process compromised the …

Semi-weekly newspaper from Livingston, Texas that includes local, state and national news along with advertising.

Semiweekly newspaper from Levelland, Texas that includes local, state, and national news along with advertising.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he is speaking at a podium.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he is speaking at a podium.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he is standing at a podium with a microphone.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. This is a photo of Mr. Flores looking downward.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he and other man are sitting at a table and reviewing documents.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he and another man are sitting at a table and studying some papers.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he and other man are sitting at a table, viewing some papers.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he is speaking on a cellular phone with large windows and what appears to be a large piece of sculpture in the background.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he is speaking on a cellular phone.

Hector Flores has served as National President of the League of United Latin American Citizens, Director of Recruitment and Retention for the Dallas Independent School District, and an Equal Opportunity Specialist for the Office of Civil Rights within the Department of Health, Education, and Welfare. In this photo, he is talking on a cellular phone.

Domingo Garcia is a practicing attorney in Dallas, Texas. Garcia served as Mayor Pro Tem of Dallas, as a Dallas City Council member, and as a Texas legislator. He is the current General Counsel for the League of United Latin American Citizens (LULAC), a Latino civil rights organization.

Domingo Garcia is a practicing attorney in Dallas, Texas. Garcia served as Mayor Pro Tem of Dallas, as a Dallas City Council member, and as a Texas legislator. He is the current General Counsel for the League of United Latin American Citizens (LULAC), a Latino civil rights organization.

Domingo Garcia is a practicing attorney in Dallas, Texas. Garcia served as Mayor Pro Tem of Dallas, as a Dallas City Council member, and as a Texas legislator. He is the current General Counsel for the League of United Latin American Citizens (LULAC), a Latino civil rights organization.

Domingo Garcia is a practicing attorney in Dallas, Texas. Garcia served as Mayor Pro Tem of Dallas, as a Dallas City Council member, and as a Texas legislator. He is the current General Counsel for the League of United Latin American Citizens (LULAC), a Latino civil rights organization.

Domingo Garcia is a practicing attorney in Dallas, Texas. Garcia served as Mayor Pro Tem of Dallas, as a Dallas City Council member, and as a Texas legislator. He is the current General Counsel for the League of United Latin American Citizens (LULAC), a Latino civil rights organization.

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Chickasha, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Sapulpa, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.

Semiweekly newspaper from Carthage, Texas that includes local, state, and national news along with advertising.