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Biomedical subjects

S M Strasberg

Publications and source records attributed to S M Strasberg.

143 records · Page 8Linked to original sources
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Anatomy, visualization and sampling of the biliary tree in animals and man.

Difficulties in obtaining proper bile samples are due to inaccessibility of the biliary tree and to distortions induced by sampling methods. One must be cognizant of the effects of diet on bile secretion and gallbladder motility. Experimental methods which interrupt the enterohepatic circulation or alter the intestinal migrating myoelectric complex induce spurious changes in bile flow and composition. Biliary tract pressure-flow relationships must be maintained or the gallbladder will be made functionless. Dead space errors lead to distortions unless studies are performed in the steady state, or dead space is measured and corrections are applied. Surgery has major effects on some parameters of interest, and animals should be allowed to recover when these are studied. The effect of the mixing of bile with other secretions in the duodenum must be considered when using bile-rich duodenal fluid. For some parameters of bile secretion, mixing is unimportant but for others, special precautions for handling bile and interpreting results are required.

Animals↗
PubMedDate not supplied

Techniques for studying biliary secretion: electrolytes in bile.

A major limitation in understanding bile formation has been technical. The liver and ductular epithelium are relatively inaccessible, necessitating indirect techniques of uncertain validity. This is well seen in attempts to define the role of electrolyte secretion in bile. It is widely agreed that bile salts stimulate a component of canalicular flow and that inorganic electrolyte secretion is stimulated by bile salts. The choleretic efficiency of a bile salt is directly related to the magnitude of the electrolyte effect. But there is no consensus regarding how and where bile salts stimulate electrolyte secretion. Some evidence points to a paracellular route by processes of solvent drag and diffusion. Other studies suggest stimulation of specific transcellular electrolyte pathways. It has been believed that canalicular bile salt-independent bile flow is generated by active blood-to-bile electrolyte transport. Actually, available methods do not permit us to conclude with absolute certainty that there is canalicular bile salt-independent flow, although there is considerable evidence for it. New studies suggest that electrolyte transport in this type of flow is passive and that flow is due to transport of organic anions. Ductular flow does seem to be due to active transport of electrolytes, particularly bicarbonate. Better and more direct techniques are required to settle the controversies in this area.

Animals↗
PubMedDate not supplied

Evidence for a nucleation defect in bile from gallstone patients.

When modern methods of estimating cholesterol saturation in bile were first applied to human bile samples, it seemed that a clear distinction could be made between normal and abnormal biles on the basis of cholesterol saturation. Supersaturation of bile with cholesterol appeared to be the only critical defect required for stone formation. A variety of evidence has now accumulated which indicates that a nucleation defect is also important. Chief among these observations is the fact that gallbladder bile from stone patients nucleates cholesterol crystals more rapidly than equally saturated gallbladder bile from controls. To determine whether the gallbladder contributes to the nucleation defect, hepatic and gallbladder bile nucleation times have been compared. Although the former is more supersaturated, the latter nucleates faster suggesting that the gallbladder is important. In another study, the nucleation times of crystal-free abnormal bile, normal bile and a mixture of the two were obtained. The mixture nucleated as rapidly as the abnormal bile even when the abnormal bile contributed only 5% of the volume of the mixture. This indicated that a nucleating factor is added to abnormal bile in the gallbladder.

Bile↗
PubMedDate not supplied

Quantitative analysis of major, minor and trace elements in gallbladder bile of patients with and without gallstones.

The concentration of 25 major, minor and trace elements in human bile was determined by inductively coupled plasma atomic emission spectrometry. Gallbladder bile was obtained during surgery from patients with cholesterol gallstones, pigment stones and with no biliary tract abnormalities (controls). Comparison of the concentration of elements (microgram per gram of solids) did not reveal any significant differences among the three patient groups. The in vitro nucleation time was not related to the concentration of any element measured.

Bile↗
PubMedDate not supplied

Evidence for a channel for the electrogenic transport of chloride ion in the rat hepatocyte.

Chloride is the major inorganic anion in bile but its mechanism of passage from blood to bile is uncertain. Specific membrane channels account for most net inorganic anion flux in other cell types such as the proximal tubular cell and red blood cell; disulfonic stilbenes inhibit anion movement through these channels. Therefore, we have sought the presence of similar channels in the hepatocyte. Net inorganic anion flux or conductance was initiated in isolated rat hepatocytes by valinomycin in the presence of an outward potassium gradient. Potassium concentration in the extracellular medium increased from 2.75 +/- 0.02 in control cell suspensions to 3.15 +/- 0.04 in valinomycin-treated cell suspensions. Membrane potential difference (Em) (mV), determined as the distribution of [14C]tetraphenyl phosphonium ion was -28 mV in control cells and -42 mV in valinomycin-treated cells (p less than 0.05). Intracellular chloride concentration (36Cl-) (mEq per liter of cell water) decreased significantly from 38.6 in control cells to 32.0 in valinomycin-treated cells. The observed intracellular concentrations (36Cl-) in both control and valinomycin-treated cell suspensions closely approximates values predicted on the basis of the Nernst equation: 41 and 29 (mEq per liter of cell water), respectively, suggesting that the chloride ion is passively distributed on the basis of the membrane potential difference. Furthermore, net rate-limited cell water loss of approximately 15% of control values was associated with the above valinomycin-stimulated changes in ion distribution, as assessed using three methods of cell water volume determination.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMedDate not supplied

Results of a new strategy for reconstruction of biliary injuries having an isolated right-sided component.

Poor results after repair of biliary injuries are most common when injuries are above the bifurcation of the left and right hepatic ducts or involve aberrant ducts. We have developed a novel approach to the right-sided component of such injuries. Preoperatively all isolated sections of the biliary tree are intubated percutaneously. At surgery the left duct is found by the Hepp-Couinaud approach. Dissection is continued to the right, staying within the coronal plane of the left hepatic duct, and continuing across the gallbladder plate into segment 5 between the hepatic parenchyma and the Wallerian sheath of the right portal pedicle. Hepatic parenchyma, anterior to the sheath, is resected. After a length of portal pedicle is exposed, right-sided bile ducts are opened on their anterior surface, using the percutaneous transhepatic stents as a guide, and hepaticojejunostomy is performed. Twenty-three patients were treated from May 1993 to February 1999. Injury types and (number of patients) were as follows: B (n = 2), C (n = 5), E4 (n = 10), and E5 (n = 6). There were no perioperative deaths. Follow-up ranged from 8 months to 7 years (median 3 years). There have been no cases of restricture, reoperation, or jaundice, and no interventional procedures. Serum bilirubin is normal in all patients. Alkaline phosphatase is normal or less than two times the normal value in 21 of 22 living patients. This novel approach brings the benefits of the Hepp-Couinaud approach to the right hepatic ducts. Very satisfactory results were obtained in the most severe types of biliary injury.

Adolescent↗