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N Prendergast

Publications and source records attributed to N Prendergast.

7 recordsLinked to original sources
PubMed1995

Effect of magnetic resonance exposure combined with gadopentetate dimeglumine on chromosomes in animal specimens.

RATIONALE AND OBJECTIVES: We tested for the presence of a form of unstable chromosomal damage--anaphase bridges--that might result from the combined exposure to gadopentetate dimeglumine and magnetic resonance (MR) imaging in rats. METHODS: Fifty-four male Sprague-Dawley rats, along with appropriate controls, were exposed either to MR imaging alone, gadopentetate dimeglumine alone, or a combination of the two. After exposure, partial hepatectomies were performed to induce a vigorous mitotic response in the regenerating liver stump. Twenty-eight to 30 hr after partial hepatectomy, tissue specimens from regenerating liver were removed and analyzed microscopically for the presence of anaphase bridges. RESULTS: No anaphase bridges were detected in any of the animals, including those exposed to gadopentetate dimeglumine and MR imaging. CONCLUSION: Using anaphase bridge formation as an indicator, exposure to MR imaging alone, gadopentetate dimeglumine alone, or a combination of the two under the conditions used in this experiment did not cause detectable unstable chromosomal damage.

Anaphase↗
PubMed1995

Normal anatomy of the hand and wrist.

An understanding of the anatomy is invaluable when such small structures as described here are to be evaluated. Because MR imaging reveals greater detail, radiologists are obliged to use the information available to benefit the clinician and the patient. A working knowledge of the anatomic elements and their nomenclature also engenders confidence in the imager on the part of the hand surgeon. This discussion serves as the basis for meaningful comprehension of the pathologic entities that are presented in the articles that follow.

Collateral Ligaments↗
PubMed1992

Magnetic resonance imaging of the shoulder joint.

Because the shoulder is the most mobile joint in the body, it is naturally predisposed to several disorders. The most commonly encountered disorders requiring diagnostic imaging are rotator cuff disease and glenohumeral instability. Plain film radiography and arthrography have for many years been the mainstays of shoulder imaging. CT added a third dimension to shoulder imaging, improving its sensitivity with respect to glenoid labral pathology. Ultrasonography of the rotator cuff showed early promise in noninvasive evaluation of cuff tears, but it did not gain universal acceptance because of various negative factors, including inadequate visualization of the cuff, poor results regarding partial tears, and most importantly, operator dependency. The development of MR imaging afforded the radiologist improved comprehensive visualization of the shoulder joint in a noninvasive manner.

Humans↗
PubMed1988

Kinetics of the formation and isomerization of methotrexate complexes of recombinant human dihydrofolate reductase.

The kinetics of inhibitor binding to highly purified recombinant human dihydrofolate reductase (rHDHFR) have been examined. Methotrexate (MTX) binds rapidly (kon = 1.0 x 10(8) M-1 s-1) and tightly (koff/kon = 210 pM) to the preformed complex of rHDHFR with NADPH. The initial association reaction between rHDHFR.NADPH and MTX is followed by an isomerization of the resulting complex (kiso = 0.4 s-1) leading to a new conformer in which MTX is bound even more tightly (Ki = 3.4 pM). Similar results have been obtained with a major metabolite of MTX having four additional glutamate residues for which Ki = 1.4 pM. 7-HydroxyMTX, another major metabolite of MTX, is a weak inhibitor of rHDHFR (Ki = 8.9 nM), and a polyglutamate form of this metabolite is an equally weak inhibitor (Ki = 9.9 nM), so that the addition of glutamate residues to MTX or 7-hydroxyMTX has little effect on their binding. It follows that the significance of MTX polyglutamate formation relates to other roles such as increasing the cytotoxicity of MTX by prolonging intracellular retention of the drug. Another antifolate, trimethoprim, binds tightly to dihydrofolate reductases from bacterial sources, but weakly to rHDHFR in the ternary complex (KD = 0.5 microM). Although the association step is rapid (kon = 0.4 x 10(8) M-1 s-1), the dissociation rate is also rapid (koff = 15 s-1). Furthermore, there is no isomerization of the ternary complex of trimethoprim with rHDHFR, in contrast to the known isomerization of complexes of trimethoprim with bacterial dihydrofolate reductases.

Escherichia coli↗