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Biomedical subjects

R C Dickson

Publications and source records attributed to R C Dickson.

At least 109 records · Page 6Linked to original sources
PubMed1978

Molecular cloning and expression in E. coli of a yeast gene coding for beta-galactosidase.

The yeast Kluyveromyces lactis synthesizes a beta-galactosidase (EC 3.2.1.32) which is inducible by lactose. We have isolated the gene that codes for this enzyme using recombinant DNA techniques. K. lactis DNA was partially digested with the restriction endonuclease Eco R1 and joined to Eco R1-digested pBR322 plasmid DNA using DNA ligase. ligase. A lac-mutant of Escherichia coli lacking the structural gene for beta-galactosidase was transformed with ligated DNA. Three lac+ transformants containing recombinant plasmids were selected. Two of the plasmids (pK15 and pK17) contain four Eco R1-K. lactis DNA fragments having molecular weights of 2.2, 1.4, 0.55 and 0.5 x 10(6) daltons. The other plasmid (pK16) lacks the smallest fragment. E. coli carrying any of these plasmids produce beta-galactosidase activity that has a sedimentation coefficient and immunological determinants that are nearly identical to K. lactis beta-galactosidase and distinctly different from E. coli beta-galactosidase. DNA-DNA hybridization studies show that the four Eco R1 fragments in pK15 hybridize to K. lactis but not to E. coli DNA.

DNA, Recombinant↗
PubMed1975

Genetic regulation: the Lac control region.

The nucleotide sequence of the lac promoter-operator region has been determined. The 122 base pairs comprising this region include the recognition sites for RNA polymerase, the positive regulatory protein, CAP, and the negative regulatory protein, the repressor. Identification of mutant variants of the sequence combined with the in vitro biochemical studies of others has allowed us to tentatively identify the recognition site for each of these proteins, and to suggest how CAP might act at a distance to affect the interaction of RNA polymerase with the promoter.

Base Sequence↗
PubMed1972

Cholestyramine and medium-chain triglyceride in prolonged management of patients subjected to ileal resection or bypass.

The pathophysiology of cholerrheic enteropathy is described and a series of patients reviewed. Of 11 patients with chronic disabling diarrhea and steatorrhea after ileal resection or bypass, two had recurrent ileitis, three had lactose intolerance and six of those operated on five years or more previously had vitamin B(12) deficiency. Cholestyramine was given alone or with medium-chain triglyceride (MCT) or Portagen (MCT and lactose). The maximal response occurred when cholestyramine was given with Portagen - significantly reduced stool frequency and weight in all patients and stool fat in five. Restudy of five patients four to 11 months later showed the same pattern of response: cholestyramine with 70% MCT abolished symptoms in four patients (ileectomy) and 100% MCT alone greatly improved the condition of the fifth (extensive small bowel resection).

Adolescent↗
PubMed1971

Ultraviolet light: a new stimulus for the induction of platelet aggregation.

Exposure to ultraviolet light (253.7 nanometers) causes mammalian blood platelets to aggregate. Aggregation is markedly enhanced in the presence of extracellular fibrinogen and is followed by the grodual of relatively small amounts of nucleotide and serotonin. Aggregation is inhibited by ethylenediamine tetraacetic acid or a combination of 2-deoxy-D-glucose and antimycin A. Adenosine, apyrase, and prostaglandin E(1) produced slight inhibition. The effect of exposure to ultraviolet light is cumulative and lasting. This agent may be used to study the process of platelet aggregation after the removal of the stimulus, by delaying the addition of fibrinogen until after cessation of irradiation. Thus ultraviolet light is the first agent known which may be used to study platelet aggregation in a period following its removal.

Animals↗