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Biomedical subjects

P F Malet

Publications and source records attributed to P F Malet.

At least 19 recordsLinked to original sources
PubMed1990

Nonvisualized gallbladder on oral cholecystography: implications for lithotripsy.

Currently, most protocols evaluating the efficacy of gallstone lithotripsy require a visualized gallbladder on oral cholecystography (OCG). The primary purpose of the OCG is to establish that the cystic duct is patent. When the gallbladder is visualized on OCG, it can also be used to number and size gallstones accurately. Patients with non-visualization of the gallbladder on OCG are excluded from consideration for lithotripsy. The purpose of this study was to evaluate retrospectively the ultrasonographic findings (i.e., number and sizes of stones in 32 patients with nonvisualization on the OCG). In 11 patients (34%) ultrasound (US) did not detect any stone, and it is presumed that the gallbladder failed to visualize for other reasons. Six patients (19%) had one or two stones and 15 (47%) patients had more than three stones. This suggests that 20% of patients with nonvisualization of the gallbladder on OCG would otherwise be eligible for lithotripsy provided that patency of the cystic duct can be demonstrated by other means, such as computed tomographic (CT) examination with oral biliary contrast or cholescintigraphy.

Cholecystography↗
PubMed1990

Intact stones or fragments? Potential pitfalls in the imaging of patients after biliary extracorporeal shock wave lithotripsy.

Ultrasound is used after extracorporeal shock wave lithotripsy of gallbladder stones to assess fragmentation. In many patients with apparently successful fragmentation, the posttreatment studies show an intraluminal, echogenic focus within the gallbladder, with posterior acoustic shadowing characteristic of an intact stone. Cholesterol gallstones were fragmented in vitro by means of lithotripsy, and the sonographic appearance of the fragmented stones was followed up over time to study factors that might affect the process. After lithotripsy, fragments settled and produced an echogenic focus with posterior shadowing indistinguishable from the appearance of an intact stone. These experimental observations led to the development of a clinical maneuver to overcome the diagnostic pitfalls posed by the reaggregation of stone fragments in situ. This rollover maneuver helps distinguish between intact stones and fragments, and prevents both diagnostic errors in follow-up and unnecessary retreatment.

Cholelithiasis↗
PubMed1990

Gallstone composition in relation to buoyancy at oral cholecystography.

Although it is recognized that some gallstones float at oral cholecystography, the reasons for this are not known. To determine how stone type and composition are related to stone buoyancy, the authors analyzed gallstones from 90 patients in the National Cooperative Gallstone Study. Seventeen patients had floating and 73 had nonfloating radiolucent stones at oral cholecystography. Stone analysis showed that all 17 floating stones were cholesterol stones; 64 of the nonfloating stones were cholesterol stones, while nine were pigment stones. The cholesterol contents of floating and nonfloating cholesterol stones were similar, 90.4% +/- 1.7 and 87.0% +/- 1.2 of stone weight, respectively. The calcium salt content of the nonfloating cholesterol stones was 3.2% +/- 0.6, while that of the floating cholesterol stones was only 1.1% +/- 0.4 (P = .02). The results indicate that floating gallstones are cholesterol stones with a significantly lower calcium salt content than that of nonfloating cholesterol stones.

Cholecystography↗
PubMed1989

Bile and stone analysis in two infants with brown pigment gallstones and infected bile.

Two infants under 3 mo of age who presented with obstructive jaundice secondary to cholelithiasis are reported. Neither infant had any congenital anatomic abnormality of the biliary tract leading to stasis, yet both had cultures of gallbladder bile that grew abundant bacteria. In both, recovery of gallbladder bile and sludge or actual stones allowed a detailed analysis of bile and stone composition. Bile was not saturated with cholesterol. In both cases, unconjugated bilirubin accounted for a large percentage of the total bile biliary pigments measured, and stercobilin was present in gallbladder bile. Bile beta-glucuronidase activity was higher when measured at the optimal pH of bacterial rather than tissue beta-glucuronidase. Analysis of stone morphology and composition showed characteristics of brown pigment gallstones with a layered appearance and the presence of calcium palmitate. This is the first report of detailed bile and stone analysis in infants and supports the hypothesis that brown pigment gallstones form spontaneously in infants who have bacterial infections in the biliary tract.

Bile↗
PubMed1989

Gallbladder mucin and cholesterol and pigment gallstone formation in hamsters.

We measured gallbladder mucin production by hamsters fed diets lithogenic for either cholesterol or pigment gallstones. In hamsters on the cholesterol stone diet, gallbladder production of 3H-glucosamine-labeled mucin was elevated two- and seven-fold after 1 and 3 weeks, respectively. After 1 week cholesterol crystals were seen in a mucus gel on the gallbladder surface. In hamsters on the pigment stone diet, gallbladder mucin production was significantly elevated after 1 and 3 weeks. The first precipitation of pigment crystals was in mucus in bile or on the gallbladder surface. Black pigment stones grew by agglomeration of pigment crystals enmeshed in mucus. In conclusion, gallbladder mucin production is increased before cholesterol or pigment stone formation, and the earliest deposition of crystals is in mucus in bile or on the gallbladder surface.

Animals↗