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Biomedical subjects

D J Reed

Publications and source records attributed to D J Reed.

At least 181 records · Page 10Linked to original sources
PubMed1966

Metabolism of red beet slices I. Effects of washing.

The changes in relative participation of pathways of glucose catabolism in red beet slices during washing have been examined using specifically (14)C labeled glucoses. Washing of these slices brings about an increase in participation of the pentose phosphate pathway. The composition of the washing medium influences slightly the extent of change in pathway participation. The activity level of certain enzymes participating in the initial stages of glucose catabolism has been measured in fresh and washed beet slices. Fresh slices which barely metabolized gluconate were found to have very little 6-phosphogluconate dehydrogenase activity. Washing brings about a dramatic increase in 6-phosphogluconate dehydrogenase activity and this increase was accompanied by a marked increase in the ability of the slices to metabolize gluconate. In red beet slices the TPNH generated via pentose phosphate pathway appears to be utilized for biosynthetic reductions rather than as respiratory substrate.

Journal Article↗
PubMed1966

Metabolism of Red Beet Slices II. Effects of Aging.

The rate of respiration of red beet slices increased 3- to 4-fold when the slices were aged in a moist atmosphere for 18 to 24 hours. The respiration of fresh slices was severely inhibited by 8 x 10(-5)m HCN but as slices aged the sensitivity of respiration to HCN fell rapidly. The presence of HCN stimulated the respiration of slices after 8 to 12 hours of aging.The relative participation of the pentose phosphate pathway in the glucose catabolism increased very little, if any, during aging of slices prepared from beets in the growing phase although the total metabolic rate seems to be greatly increased. However, data obtained from slices prepared from dormant beets indicated a possible increase in pentose phosphate pathway participation in glucose catabolism upon aging. The activity of 6-phosphogluconate dehydrogenase increased very markedly during aging and a corresponding marked increase in the ability of the tissue to metabolize gluconate was observed. It is concluded that to associate the aging process of storage tissue slices with a specific increase in a particular pathway is not justifiable.

Journal Article↗
PubMedDate not supplied

Identification of the reactive glutathione conjugate S-(2-chloroethyl)glutathione in the bile of 1-bromo-2-chloroethane-treated rats by high-pressure liquid chromatography and precolumn derivatization with o-phthalaldehyde.

The conjugation of glutathione with 1,2-dihaloethanes leads to the formation of S-(2-haloethyl)glutathione which, following intramolecular cyclization, produces an electrophilic thiiranium ion. The extent to which the formation of the thiiranium ion is responsible for the toxicity associated with 1,2-dihaloethanes has been difficult to determine because of the inherent instability of the compound under physiological conditions. The goal of this study was to attempt to identify a putative precursor of the thiiranium ion, S-(2-chloroethyl)glutathione (CEG), in the bile of rats treated with 1,2-dihaloethanes such as 1-bromo-2-chloroethane (BCE). In order to detect the presence of CEG, a precolumn procedure for derivatizing the amine of CEG with o-phthalaldehyde/2-mercaptoethanol (OPA/MCE) was developed. Studies with a model compound, S-ethylglutathione, indicated that the derivatization reaction between S-ethylglutathione and OPA/MCE proceeded rapidly and under mild conditions. The resulting fluorescent adduct of S-ethylglutathione was detected at low concentrations following separation by reverse-phase HPLC. Derivatization of CEG with OPA/MCE followed by preparative HPLC and mass spectral analysis revealed that the major fluorescent adduct in the reaction mixture was the expected 1-[(2-hydroxyethyl)thio]-2-substituted-isoindole derivative of CEG. Also present in the derivatization reaction mixture were small quantities of S-(2-hydroxyethyl)glutathione, the product of CEG hydrolysis, and a product involving the addition of MCE to CEG. Analysis of the bile samples obtained from bile-cannulated rats treated with BCE showed the presence of a peak corresponding to CEG. Over a 3-h interval, 2% of the BCE administered was excreted into the bile as CEG.

Animals↗