Biomedical subjects

T Brennan

Publications and source records attributed to T Brennan.

4 recordsLinked to original sources

PubMed1979

Inability to demonstrate hydroxylation of tyrosine by murine melanoma "tyrosinase" (L-DOPA oxidase), using the tritiated water assay technique.

Validity of the tritiated water assay technique for tyrosine hydroxylase activity as a qualitative method was demonstrated with mushroom tyrosinase. Using this method, isolated murine melanoma "tyrosinase" (L-dopa oxidase) showed no tyrosine hydroxylase activity. This finding supports previous studies in our laboratory which used a variety of histochemical and biochemical methods. The nonenzymatic production of tritiated water caused by tritium exchange with hydrogen peroxide complicates the use of the tritiated water assay technique with crude systems, since hydrogen peroxide is generated by a variety of oxidase reactions. For this reason, previous studies using the tritiated water assay technique with crude systems are ambiguous.

Animals↗

PubMed1976

Structlre of transfer RNA molecules containing the long variable loop.

A structure is proposed for the type II tRNA molecules containing the long variable loop and the tertiary base interactions here are compared with type I tRNAs having the short variable loop. The type II tRNAs are similar to the type I tRNAs in their tertiary base pairing interactions but differ from them generally by not having the tertiary base triples. The long variable loop, which is comprised of a helical stem and a loop at the end of it, emerges from the deep groove side of the dihydrouridine helix, and is tilted roughly 30 degrees to the plane formed by the amino acid-pseudo-uridine and anticodon-dihydrouridine helices found in yeast tRNAPhe. The fact that many of the type I tRNAs also lack the full compliment of base triples suggests that the tertiary base pairs may alone suffice to sustain the tRNA fold required for its biological function. The base triples and the variable loop appear to have little functional significance. The base type at position 9 is correlated with the number of base triples and G-C base pairs in the dihydrouridine stem.

Base Sequence↗

PubMed1976

Atomic coordinates and molecular conformation of yeast phenylalanyl tRNA. An independent investigation.

The atomic coordinates of yeast tRNA(Phe) in the monoclinic crystal form have been determined by an independent analysis from a model built into a 3 A MIR map. The overall molecular structure is found to be in agreement with those reported for the same crystal form by Ladner et al. (1975) and for the orthorhombic form by Quigley et al. (1975) and Kim et al. (1975). However, significant differences between any two of the four models are found in certain local regions of the molecule. The structure is analyzed in terms of the nucleotide stereochemistry and internucleotide phosphodiesters. A striking observation is that the majority of the nucleotide moieties occur in the conformation preferred by the constituent mononucleotides themselves. The internucleotide P-O bonds afford the primary source of flexibility for the folding of the polynucleotide backbone while the sugar pucker and C(4')-C(5') torsions provide the secondary source of flexibility.

Binding Sites↗

PubMedDate not supplied

EPAP without intubation.

The early institution of end expiratory pressure has been demonstrated frequently to be beneficial in acute respiratory failure. EPAP without intubation allows early therapy while avoiding the complications associated with the high flow rates utilized with CPAP. Three patients are described, illustrating the administration of EPAP for mild ARDS, aspiration penumonia, and postoperative atelectasis.

Adolescent↗