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Biomedical subjects

P M Loeb

Publications and source records attributed to P M Loeb.

At least 19 recordsLinked to original sources
PubMed1989

Choledochal cyst.

A 16-year-old girl with recurrent pain in the right upper quadrant and abnormal results of liver function tests was found to have a large choledochal cyst filled with stones. Computerized tomography and endoscopic retrograde cholangiopancreatography showed the large cyst with innumerable primary cyst stones and an anomalous pancreaticobiliary duct junction.

Adolescent↗
PubMed1987

Massive colonic dilatation as initial presentation of mesenteric vein thrombosis.

The case of a patient with primary mesenteric venous thrombosis presenting with massive dilatation of almost the entire colon is described. The differential diagnosis suggested by this presentation is briefly discussed with special attention to the diagnosis of acute colonic pseudoobstruction. Possible reasons for the atypical presentation of acute mesenteric venous thrombosis should, therefore, be considered in the differential diagnosis of all patients presenting with colonic distention and pseudoobstruction.

Acute Disease↗
PubMed1979

Determinants of the rate of intestinal absorption of oral cholecystographic contrast agents in the dog jejunum.

Successful opacification of the gallbladder during oral cholecystography depends on adequate absorption of the contrast agent from the intestine. The present studies were undertaken to define the specific characteristics of the intestinal mucosa and the properties of the various contrast agents which determine their rates of intestinal absorption. The polarity of the compounds was established by determining the ratios of their distribution between bulk solvents (benzene and water). In addition, the maximum aqueous solubility of each compound was determined. Using in vivo cannulated segments of dog jejunum, apparent passive permeability coefficients were measured. From these data, the apparent maximal rate of intestinal absorption was calculated. The six cholecystopaques studied differed markedly in polarity as judged by their varying ratios of distribution between benzene and water. The permeability coefficients varied inversely with the polarity of the compounds. However, the incremental changes in the coefficients were considerably less than the corresponding changes observed in the partition ratios. The rates of absorption of the more polar contrast agents (tyropanoate, iopronic acid, and iocetamic acid) were greater than the less polar compounds (iopanoic acid, sodium ipodate, and calcium ipodate) under the conditions in which the resistance of the unstirred water layer is not rate limiting and where bile acid micelles are not present.

Animals↗
PubMed1978

The effect of fasting on gallbladder opacification during oral cholecystography: a controlled study in normal volunteers.

The effect of fasting on gallbladder opacification during oral cholecystography was studied in 10 normal volunteers using 2 oral cholecystographic agents, iopanoic acid and sodium tryopanoate. Radiographs made 15 hours after ingestion of the contrast agents revealed good opacification of the gallbladder in all subjects when iopanoic acid was administered with a meal and when sodium tyropanoate was administered in the fasting state; in only 2 subjects when iopanoic acid was given in the fasting state; in 3 when given in the fasting state with ox bile; and in 3 when sodium tyropanoate was given with a meal.

Administration, Oral↗
PubMed1977

Influence of Cholografin and Renografin 76 on platelet function.

Cholografin and Renografin 76 were studied to determine their effects on platelet function. In vitro platelet aggregation was significantly inhibited by at least 3.4 micron/ml Cholografin and 19.5 micron/ml Renografin 76. Patients who received Cholografin for intravenous cholangiography, and Renografin 76 for non-cardiac angiography, had low levels of plasma contrast agent, and hemostasis was clinically unimpaired. Patients who received Renografin 76 for cardiac angiography had inhibition of platelet aggregation at high levels of plasma contrast agent; there was no correlation with prolonged bleeding times, or with bleeding complications. High levels of plasma contrast agent may inhibit platelet aggregation in vitro and in vivo, although this may not be associated with clinically significant bleeding.

Contrast Media↗
PubMed1977

Iotroxamide--a new intravenous cholangiographic agent. Comparison with iodipamide and the effect of bile salts.

The maximum biliary excretion rate of iotroxamide was found to be significantly greater than that of iodipamide in bile-fistula dogs. High bile salt excretion rates had no effect on the rate of biliary excretion of either compound, but the choleresis associated with greater bile salt excretion reduced the biliary concentration of both agents. Both are potent choleretics, stimulating about 23.5 ml of bile per mmole of contrast agent excreted in bile. This obligatory coupling of the contrast agents with water as they are excreted in bile imposes a limit on the maximum concentration that can be achieved in bile. Since iotroxamide is excreted more rapidly in bile than iodipamide for any equimolar plasma concentration, it may be a superior contrast agent for intravenous cholangiography.

Animals↗
PubMed1977

Experience of a physician-nurse practitioner team in care of patients in skilled nursing facilities.

The use of a physician-nurse practitioner team is advocated as an approach to delivering better health care to patients in skilled nursing facilities. The application of this approach in a young community with an inadequate supply of primary physicians and 596 extended care beds is discussed. Patients derive benefit from more comprehensive health care delivered with greater attention to individual needs. Staffs of skilled nursing facilities enjoy improved communication with the medical team and better compliance with legal requirements. The team physician is able to use his time more effectively and provide medical supervision for a greater number of patients by sharing responsibilities with a nurse practitioner. Paper compliance, adherence to agency regulations, quality assurance, and payment are some of the problems encountered.

California↗
PubMed1976

Pharmacology and physiology of the biliary radiographic contrast materials.

(1) Solubilization of Telepaque in the intestine is a limiting factor in the rate of intestinal absorption. Bilopaque and Oragrafin are more water-soluble and appear to be better absorbed than Telepaque. (2) Bile salts in the intestinal lumen increase the solubility of Telepaque. Therefore, a fatty meal administered with the Telepaque is desirable to evacuate bile salts from the gallbladder into the intestine. This is not required for the more water-soluble agents, Biopaque and Oragrafin. (3) The degree of protein binding of the contrast agents can be related to the degree of toxicity. Cholografin is the most highly bound and is the most toxic. (4) Hepatic receptor proteins may specifically bind the biliary contrast agents. This may be the reason that the renal contrast materials are poorly escreted in bile compared to the biliary contrast agents. (5) Telepaque is conjugated in the liver with glucuronide making the compound more soluble in bile. This prevents precipitation of Telepaque in the gallbladder and avoids reabsorpiton from the intestine. (6) The biliary excretion of Telepaque is facilitated by bile salts. Therefore, the administration of a fatty meal with Telepaque not only increases the rate of intestinal absorption of Telepaque but also the rate of biliary excretion. (7) The rate of biliary excretion of both the oral and the intravenous contrast agents appears to be limited by a hepatic transport maximum. Above a certain dose, increased amounts of the contrast agents do not result in more rapid excretion of the agents into bile. Rapid infusion of intravenous contrast agents results in high plasma concentration and greater urinary excretion, without increasing the biliary excretion. It does not appear to be indicated in clinical practice. (8) The biliary concentration of the contrast agents used for intravenous cholangiography is determined by their rate of biliary excretion, the choleretic effect of the contrast agent, and factors that determine the rate of basal bile flow. Fixed coupling of water with the biliary excretion of these contrast agents imposes an inherent limitation on the concentration of the contrast agent in bile. It appears that the biliary concentration of the intravenous contrast materials can be increased by having the patient fast prior to intravenous cholangiography. This decreases the enterohepatic circulation of bile salts and the rate of bile-salt-dependent bile flow. (9) Failure of the gallbladder to visualize after administration of Telepaque when there is adequate biliary excretion may be due to cystic duct obstruction, failure of the inflamed gallbladder mucosa to reabosrb water, or reabsorption or the contrast agent by the diseased gallbladder mucosa. (10) Maximum concentration of Telepaque occurs at 14-19 hr after ingestion. It is at this time that radiographs of the gallbladder should be made. With Bilopaque, peak concentration occurs at 10 hr so radiographs can be made earlier when Bilopaque is used.

Animals↗
PubMed1976

Saturation kinetics and choleretic effects of iodoxamate and iodipamide.

The biliary excretion and choleretic effects of iodoxamate (Cholevue) and iodipamide (Cholografin) were compared in unanesthetized dogs with biliary fistulas in order to assess the potential of the two contrast agents for use in intravenous cholangiography. For any equimolar infusion rate, more iodoxamate was secreted in the bile than iodipamide was the same. At the constant basal bile flow maintained in these studies, there was no difference in the maximum biliary concentration of the two compounds. With the presently recommended doses, it is unlikely that iodoxamate will offer a striking improvement over iodipamide for intravenous cholangiography in patients with normal liver function.

Animals↗
PubMed1976

The biliary and urinary excretion of iopanoic acid: pharmacokinetics, influence of bile salts, and choleretic effect. An experimental study in bile-fistula dogs.

The biliary and urinary excretion and the choleretic effect of iopanoic acid (Telepaque) were studied in nonanesthetized bile-fistula dogs using a stepwise increase of infusion rates of iopanoic acid and a constant infusion of sodium taurocholate at a rate of either 0.5 or 2.0 mumoles/min./kg. The maximum rate of bile excretion (0.671 mumoles/min./kg) when taurocholate was infused at the lower rate nearly doubled (1.325 mumoles/min./kg) when given at the higher rate. Maximum biliary concentrations of iopanoic acid at both rates of taurocholate infusion (70-77 mumoles/ml) were almost double the maximum concentration previously determined for iodipamide (Cholografin) (42 mumoles/ml).

Animals↗
PubMed1975

The choleretic effect of iodipamide.

It is well established that a number of organic anions are excreted by the liver into bile in association with a marked increase in bile flow. Previous studies have shown that iodipamide (3,3'-(adipoyl-diimino)bis[2,4,6-triiodobenzoic acid]), the radiographic contrast material used for intravenous cholangiography, is a potent choleretic. Experiments were performed in unanesthetized dogs to determine if the increased bile flow produced by iodipamide is canalicular or ductular in origin, to quantitate the choleresis associated with iodipamide and taurocholate excretion, and to correlate these findings with the results of in vitro studies in which the osmotic activities of iodipamide and taurocholate in both isotonic saline and bile were determined. The plasma erythritol clearance increase linearly with the excretion of iodipamide, indicating that iodipamide stimulates canalicular bile flow. The choleretic potency of iodipamide (22 ml/mmol) is approximately 3 times that of taurocholate (7.8 ml/mmol), yet the osmotic activity of iodipamide in bile (1.5 mosmol/mmol) is only twice as great as that of taurocholate in bile (0.8 mosmol/mmol). It therefore appears that, per unit of effective osmotic solute secreted, iodipamide carries more water into the bile canaliculi than does taurocholate.

Animals↗
PubMed1975

Biliary excretion of iodipamide.

Conflicting data have been reported concerning the optimum dose and rate of administration of iodipamide required to obtain maximum radiographic opacification of the biliary tree during intravenous cholangiography. Experiments were performed in dogs to determine the effect of plasma concentration on the excretion and concentration of iodipamide in the bile and urine during a steady state of infusion and excretion. The data indicate that a hyperbolic relation exists between the plasma concentration and both the biliary concentration and the total biliary excretion. A mathematical expression of these relations is presented. At low plasma concentrations, iodipamide was not excreted in the urine. However, at high plasma concentrations, urinary excretion increased sharply. It appears that a biliary concentration of iodipamide sufficient to achieve adequate radiographic visualization of the biliary tree can be obtained without significant renal excretion by constant infusion of iodipamide at an appropriate rate in dogs. Stepwise increase in the infusion rate until adequate radiographic visualization is obtained may be the best method for performing intravenous cholangiography to obtain visualization with the least amount of iodipamide in order to minimize toxicity.

Animals↗