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Biomedical subjects

M Shanahan

Publications and source records attributed to M Shanahan.

At least 37 records · Page 2Linked to original sources
PubMed1989

Effect of molecular charge on para- and transcellular access of horseradish peroxidase into rat bile.

The permeability pathway into the biliary tree for small inert molecules exhibits a charge selectivity. Using a method which distinguishes trans- from paracellular access, we have examined the charge selectivity of biliary access pathways for the 40-kD protein horseradish peroxidase (pI 7.5), which was derivatized to strongly anionic (pI less than 3.5) and strongly cationic (pI greater than 9.5) isoenzymes. Each isoenzyme was injected as a bolus into the perfusate of an isolated rat liver perfused in situ with a nonrecirculating Krebs-Ringer buffer. Bile was collected at intervals and horseradish peroxidase activity was measured. Its appearance allowed differentiation of paracellular from transcellular access, and the amount entering via each pathway was quantified. The species of enzyme entering bile was the same as that injected as determined by cation-exchange high-performance liquid chromatography of biliary horseradish peroxidase. Paracellular biliary access of anionic horseradish peroxidase was less than 50% that of neutral and cationic horseradish peroxidase both in the control state and when paracellular entry was augmented with 10(-10) M vasopressin. Transcellular access of anionic horseradish peroxidase was similarly restricted. To determine whether this restriction of anionic transcellular access was brought about by diminished hepatocellular uptake or augmented catabolism, we studied these parameters in 4-hr primary hepatocyte cultures. The uptake rates of all species were similar. Little or no degradation or efflux of any horseradish peroxidase species occurred over 30 min in the cultured cells. We conclude that access is charge selective for macromolecules and that this selectivity holds for trans- as well as for paracellular pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

New JCAHO QA/RM venture. Interview by David Bushelle.

An interview with JCAHO's Maryanne Shanahan describes a first-of-its-kind publications package introduced to help organizations develop a computerized system for managing quality assurance and risk management information needs.

Accreditation↗
PubMed1987

Mechanisms of the development and resolution of paradoxical interventricular septal motion after uncomplicated cardiac surgery.

Of 16 patients with normal preoperative left ventricular (LV) function studied by simultaneous two-dimensional and M-mode echocardiography before and after uncomplicated cardiac surgery, M-mode interventricular septal motion remained normal in seven (group I) and was paradoxical in nine (group II) 7 to 13 days postoperatively, but was normal in all 12 patients (7 group II) studied 3 to 18 months later. An abnormal systolic increase in normalized septal curvature, the essential feature of truly paradoxical septal motion, was not observed in either group during any study period (mean = 0.92 +/- 0.08), nor were significant differences found in septal thickening, LV fractional shortening, or fractional area change. In contrast, systolic anterior motion of the LV center increased from -0.1 +/- 1.6 mm preoperatively to 4.8 +/- 2.5 mm postoperatively in group II (p less than 0.001), and the LV posterior wall motion:thickening ratio increased from 1.10 +/- 0.33 to 2.16 +/- 0.45 (p less than 0.01), but both parameters had returned to preoperative levels at the follow-up study. Both parameters remained stable in group I during all study periods. In addition, direct intraoperative M-mode recordings (n = 14) demonstrated normal septal motion in both groups before chest closure, but esophageal echocardiograms (n = 10) demonstrated exaggerated anterior systolic LV motion within 2 hours of surgery in those from group II. Thus, early after uncomplicated cardiac surgery, apparently paradoxical septal motion relative to a fixed reference point is an artifact due to exaggerated cardiac mobility that resolves with the progressive restraining effect of postoperative adhesions.

Adult↗