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Biomedical subjects

M C Roarke

Publications and source records attributed to M C Roarke.

6 recordsLinked to original sources
PubMed1998

Provocative imaging. Diuretic renography.

Diuretic renography remains the noninvasive functional study of choice in patients with hydronephrosis resulting from apparent UPJ obstruction. Meticulous attention to proper patient preparation, radiopharmaceutical selection, furosemide dosage and administration, and image interpretation and an awareness of potential pitfalls are essential for accurate diagnosis. For most patients, the F + 20 protocol is sufficient, however; the F-15 protocol allows clarification in cases of equivocal baseline F + 20 studies. Invasive antegrade techniques such as the Whitaker pressure/perfusion test are best reserved for patients in whom the diagnosis remains equivocal after diuretic renography, or in patients with massive hydronephrosis or renal insufficiency. New standardized protocol guidelines should help to ensure studies that are reproducible in different nuclear medicine laboratories.

Adult↗
PubMed1996

Bowel wall thickening: differentiation of inflammation from ischemia with color Doppler and duplex US.

PURPOSE: To determine whether ultrasonography (US) can be used to differentiate inflammatory from ischemic bowel wall thickening. MATERIALS AND METHODS: Thirty-five patients (aged 23-96 years) with inflammatory or ischemic bowel wall thickening underwent US. Thickness was recorded, echotexture categorized, color Doppler flow graded, presence of intramural arterial signal recorded, and resistive index calculated. RESULTS: The difference between inflammatory and ischemic bowel wall thicknesses was not significant (P = .49). Differences in color Doppler flow (P < .0001), arterial signal (P = .0005), and bowel wall echotexture (P < or = .0200) between patients with inflammatory and ischemic bowel wall thickening were significant. Absence of or barely visible color Doppler flow and absence of arterial signal suggested ischemia; readily visible color Doppler flow and a stratified echotexture suggested inflammation. A resistive index less than 0.60 indicated inflammation. The difference in resistive index between the two groups was not significant (P = .12). CONCLUSION: Duplex and color Doppler flow US are helpful in differentiation between ischemic and inflammatory bowel wall thickening.

Case-Control Studies↗
PubMed1989

Temperature-sensitive steps in the secretory pathway for von Willebrand factor in endothelial cells.

The effect of reduced temperature on the post-translational processing and stimulated release of von Willebrand factor (vWf) from human umbilical vein endothelial cells was studied. Following pulse-labeling, cells were incubated for 4 h at 18 degrees C or 20 degrees C. Post-translational processing was reversibly arrested at the dimer stage, dimers were composed of Endo H-sensitive precursor subunits, and no vWf was detected in the culture medium. This block was reversible, since warming cells to 37 degrees C relieved it and resulted in the appearance of fully processed vWf in the cells and the culture medium. The same results were obtained when cells were incubated with carbonyl cyanide m-chlorophenol hydrazone or dinitrophenol which inhibit mitochondrial oxidative phosphorylation, known to block exit of secretory proteins from the endoplasmic reticulum (ER). This indicated that ER exit is not required for the complete dimerization of vWf. Reduced temperature (18 degrees C and 20 degrees C) also reversibly and nearly completely inhibited the secretagogue-induced release of vWf from Weibel-Palade bodies without affecting the microtubular cytoskeleton. We add reduced temperature to the list of useful tools for the study of the vWf secretory pathway in endothelial cells.

Calcimycin↗