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Biomedical subjects

R Delaney

Publications and source records attributed to R Delaney.

31 records · Page 2Linked to original sources
PubMed1976

Soluble enzyme system for vitamin K-dependent carboxylation.

The vitamin K-dependent carboxylating system has been solubilized by Lubrol PX or Triton X-100 treatment of vitamin K-deficient rat liver microsomes. As obtained from vitamin K-deficient rat liver, this soluble preparation is dependent upon the in vitro addition of vitamin K1 for carboxylating activity. The enzyme system is complex and is dependent upon NADH and dithiothreitol for maximum activity. While detergents used to solubilize the enzyme complex do markedly inhibit the activity of the system, the solubilized system is still highly responsive to vitamin K addition and can be used for further study of the carboxylating enzyme system. The requirement for dithiothreitol and the inhibition by p-hydroxymercuribenzoate indicate the involvement of an --SH enzyme in the carboxylating system.

Animals↗
PubMed1976

Stimulation of adenylate cyclase by Vibrio cholerae toxin and its active subunit.

The mechanism by which Vibrio cholerae toxin and its active subunit A stimulate adenylate cyclase of rat liver plasma membrane after in vivo or in vitro exposure was investigated. Stimulation of adenylate cyclase was more efficient with cholera toxin than with subunit A in whole animals and in "soluble" preparations of adenylate cyclase. Toxin-stimulated plasma membrane adenylate cyclase activity persisted after solubilization from the membrane by detergent, while subunit A stimulation was destroyed by detergent treatment. Detergent-free "soluble" enzyme could be stimulated in vitro by cholera toxin, but such stimulation by subunit A was very weak. Binding studies with iodotoxin or iodosubunit A confirmed that the interaction of toxin with adenylate cyclase in "soluble" preparations could be the result of specific binding to the enzyme. The uncertainty as to whether G M1 ganglioside (galactosyl-N-acetylgalactosaminyl [sialosyl] lactosyl ceramide; GGnSLC) is present in these fractions limited the interpretation of the data on binding. A biological modification of subunit A prior to the activation of adenylate cyclase is inferred from these data.

Adenylyl Cyclases↗
PubMed1975

Partial purification and characterization of the enzyme which converts precursor liver protein to factor X.

A rat liver post-microsomal supernatant enzyme, which carries out an epigenetic conversion of a protein contained in liver microsomes to Factor X, has been partially purified 250-fold in 50% yield by a combination of salt fractionation and gel filtration. The crude enzyme is stable to freezing and thawing but unstable at 4 degrees C. However, the partially purified enzyme is more stable at 4 degrees C. It requires Ca2+ and HCO3 minus for optimum formation of Factor X activity. The supernatant enzyme is vitamin K dependent and exhibits its maximum rate of formation of Factor X between pH 8 and 8.5.

Animals↗
PubMedDate not supplied

The role of denial in recovery from coronary heart disease.

This longitudinal study investigated the relationship between denial of illness and the course of recovery in patients with coronary heart disease. Using a newly developed interview instrument, the Levine Denial of Illness Scale (LDIS), the level and modes of denial were assessed in 45 male patients who were hospitalized for myocardial infarction or for coronary bypass surgery, of whom 30 were followed for 1 year after discharge. The reliability, internal consistency, and validity of the LDIS were found to be satisfactory. Furthermore, the LDIS showed discriminant validity from trait measures of denial. LDIS scores were not associated with severity of illness or risk factors. High deniers spent fewer days in intensive care and had fewer signs of cardiac dysfunction during their hospitalization relative to low deniers. However, in the year following discharge, high deniers adapted more poorly than low deniers: high deniers were more noncompliant with medical recommendations and required more days of rehospitalization. The findings suggest that denial of illness is adaptive during acute hospital recovery, but is maladaptive in the long-run after hospital discharge.

Adaptation, Psychological↗