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D Whitehouse

Publications and source records attributed to D Whitehouse.

3 recordsLinked to original sources
PubMed1977

Stereoselectivity and stereospecificity of the alpha,beta-dihydroxyacid dehydratase from Salmonella typhimurium.

1. In addition to the known 2R,3R- and 2R, 3S-2,3-dihydroxy-3-methylpentanoic acids (DHI), the 1S,3S- and sS,DR-isomers were prepared. 2S-2,3-Dihydroxy-3-methylbutanoic acid (DHV) was also prepared in addition to the known 2R-isomer. 2. The six dihydroxy acids were examined for their ability to promote the growth of isoleucine-valine (ilv)-requiring strains of Salmonella typhimurium and to serve as substrates for the alpha,beta-dihydroxyacid dehydratase of the same organism. 3. Only 2R,3R-2,3-dihydroxy-3-methylpentanoic and 2R-2,3-dihydroxy-3-methylbutanoic acids supported growth of the ilv strains of S. typhimurium. 4. alpha,beta-Dihydroxyacid dehydratase utilized the three isomers with the 2R-configuration as substrates but not those with the 2S-configuration. 5. In an additional growth study that utilized the 3R- and 3S-isomers of 3-methyl-2-oxopentanoic acid, the alpha-keto acid analogue of isoleucine, only the 3S-isomer supported growth. 6. It is concluded that the mechanism of action of the dehydratase is stereospecific in that the proton that is attached to C-3 of the substrate occupies the same steriochemical position as the departing hydroxyl group (Fig. 6).

Cell Division↗
PubMedDate not supplied

Behavior and learning problems in epileptic children.

In this modern age of rapidly advancing medical knowledge and technology there are few conditions as wrapped up in ignorance and prejudice as that known as epilepsy. A large part of the reason for this lies in the concept of the "epileptic person," by which is really meant the epileptic personality. In an attempt to assess behavior and learning in children with seizures, behavior and learning being regarded as opposite sides of the same coin, a study was designed in which totally objective neurological and psychological data was obtained from such a group of children. The evaluation was carried out without any prior knowledge of the nature of the presenting clinical picture, so as to prevent bias from pre-conceived notions. The results show that 70% of the first 200 children showed significant learning defects sufficient to make special educational placement mandatory. Of the remaining 30% some still showed minor learning problems enough to give rise to difficulties in regular classroom situations. Associated with these learning problems were varying behavioral reaction types, varying from the classical hyperactive child with minimal cerebral dysfunction to many environmentally-produced behavior difficulties resulting from faulty school placement due to failure to recognize learning problems. Faculty parental handling due to similar failure to realize the child's limitations also contributed to this. The significance of these findings with respect to the behavior disturbances of the so-called epileptic child will be discussed.

Adolescent↗