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J Reichen

Publications and source records attributed to J Reichen.

At least 181 records · Page 10Linked to original sources
PubMed1983

A novel method for continuous monitoring of bilirubin production in unstressed rats.

We describe a device for continuous infusion and monitoring of exhaled 14CO as a test of hepatic bilirubin production in rats. A Silastic catheter, implanted into a jugular vein under light ether anesthesia, was protected with a spring shield and a cannula swivel. The animals were kept in a modified Bollman cage. delta-[5-14C]aminolevulinic acid, a heme precursor yielding 14CO upon breakdown of heme to bilirubin, was infused at a constant rate. Exhaled 14CO was oxidized to 14CO2 and collected in ethanolamine. The efficiency of the system averaged 97.8%. In untreated animals 14CO production reached a plateau within 12 h; thereafter, it increased by 2.8% per day. The responsiveness of the system was tested by fasting the animals, which stimulated hepatic bilirubin production. Fasting increased 14CO production by 32.8 +/- 8% (mean +/- SD, P less than 0.005) after 72 h. This was associated with an increase in hepatic heme oxygenase activity (+48%, P less than 0.05) and a decrease in microsomal cytochrome P-450 content (-45%, P less than 0.05). Thus, our approach permits continuous monitoring of hepatic bilirubin production without subjecting the animals to the stress of handling, restraint, or anesthesia. The method can easily be applied to other breath tests involving formation of 14CO2.

Aminolevulinic Acid↗
PubMed1983

Taurocholate, but not taurodehydrocholate, increases biliary permeability to sucrose.

To determine whether bile salts alter the permeability of the biliary tree to inert solutes, we investigated the effects of taurocholate and taurodehydrocholate on [14C]sucrose bile-to-plasma ratio in the situ perfused rat liver. Sucrose bile-to-plasma ratio remained virtually constant over a 3-h period in untreated rats. Infusing increasing amounts of taurocholate produced the anticipated dose-dependent increase in bile flow and bile salt secretion up to a maximal secretory rate of 278 nmol X min-1 X g liver-1. When the secretory rate was exceeded, bile flow decreased by 22%. Even at doses below the maximal secretory rate, sucrose bile-to-plasma ratio increased in a dose-dependent fashion. To determine whether this was due to recruitment of more permeable centrizonal hepatocytes, the effect of equimolar amounts of taurodehydrocholate was determined. This nonmicelle-forming bile salt led to more marked choleresis than taurocholate but did not affect sucrose bile-to-plasma ratio. We conclude that taurocholate, but not taurodehydrocholate, leads to a dose-dependent increase in biliary permeability.

Animals↗
PubMed1983

Inflammatory polyposis in an ileal blind loop.

A case of inflammatory polyposis of the ileum after ileosigmoid anastomosis is reported. Two features are noteworthy. First, the polyps were localized in a blind ileal loop. Second, while rare ileal inflammatory polyps related to enteroenteric anastomosis have been reported, to our knowledge this is the first instance of approximately 50 polyps to be described at such a site. The etiology of these lesions is unknown but may be related to fecal irritation, stasis, bacterial overgrowth, or bacterial toxin. These polyps may ulcerate and bleed, causing iron deficiency anemia, and they must be distinguished from neoplastic polyps. Since side-to-side and end-to-side anastomoses have become more common with use of the surgical stapler, inflammatory polyps may be encountered more frequently.

Aged↗
PubMed1982

Chylous ascites after an H-graft interposition mesocaval shunt.

A case of chylous ascites occurring after an emergency mesocaval shunt is reported. After an attempt at conservative management had failed, the patient was surgically explored. Although a lymphatic leak could not be identified, oversewing the retroperitoneum in the area of previous dissection and reinforcement with an omental pedicle was successful in preventing postoperative reaccumulation of chylous ascites. A review of the 26 reported cases of postoperative chylous ascites indicates a spontaneous resolution rate of 41% with non-operative management including low fat diet, paracenteses, and total parenteral nutrition. If conservative measures fail, surgical repair of the traumatised lymphatic bed has been successful.

Adult↗
PubMed1981

The role of microfilaments and microtubules in taurocholate uptake by isolated rat liver cells.

The role of microfilaments and microtubules on bile salt transport was studied by investigating the influence of a microfilament and a microtubule inhibitor, cytochalasin B and colchicine, respectively, on taurocholate uptake by isolated hepatocytes in vitro. Hepatocytes were prepared by the enzyme perfusion method and [14C]taurocholate uptake velocity was determined by a filtration assay. Taurocholate uptake obeyed Michaelis-Menten kinetics, maximal uptake velocity and apparent half-saturation constants averaging 0.87 +/0 SD 0.05 nmol . s-1 . 10(-6) cells and 10.9 +/- 1.8 muM, respectively. Cytochalasin B (4.2-420 muM) inhibited taurocholate uptake in a competitive fashion; Ki being 33 +/- 7 muM. At concentrations above 100 muM the compound decreased 36Cl membrane potential and intracellular K+ concentration. Other parameters of cell viability were not affected by cytochalasin B. Colchicine (0.1-1.0 mM), by contrast, inhibited taurocholate uptake non-competitively, Ki being 0.47 +/- 0.07 mM. The inhibition brought about by colchicine was considerably smaller than that induced by cytochalasin B. None of the parameters of cell viability tested was affected by colchicine. These results suggest that microfilaments may be involved in the carrier-mediated hepatocellular transport of bile salts. This could, at least in part, account for cytochalasin B-induced cholestasis. The contribution of the microtubular system, if any, is less important quantitatively. The mechanisms whereby these two components of the cytoskeleton partake in bile salt transport remain to be elucidated.

Animals↗
PubMed1981

Binding of unconjugated and conjugated sulfobromophthalein to rat liver plasma membrane fractions in vitro.

As part of a study of the mechanism whereby organic anionic dyes such as sulfobromophthalein and bilirubin enter hepatocytes, the binding of [35S]sulfobromophthalein and of its glutathione conjugate to two rat liver plasma membrane fractions were studied in vitro. Both fractions reversibly and saturably bound conjugated and unconjugated sulfobromophthalein. Three classes of binding site were necessary to account for the observed sulfobromophthalein binding, their maximal binding capacities being 3.5 . 10(-11), 1.6 . 10(-7) and 5.4 . 10(-7) mol/mg membrane protein. The corresponding association constants were 5.5 . 10(7), 1.5 . 10(5) and 1.3 . 10(3) M-1. Binding of the glutathione conjugate could be accounted for by two classes of binding site only, their association constants being 2.0 . 10(8) and 1.9 . 10(3) M-1 and their maximal binding capacities 5.0 . 10(-11) and 2.2 . 10(-7) mol/mg protein, respectively. Conjugated and unconjugated sulfobromophthalein mutually competed for binding, KI being 7.8 . 10(-7) and 5.5 . 10(-5) M for conjugated and unconjugated sulfobromophthalein, respectively. Similarly, bilirubin and indocyanine green, but not taurocholate, competitively inhibited sulfobromophthalein binding. Treatment with trypsin and phospholipases reduced, while treatment with neuraminidase did not affect binding. Neither changes in pH nor substitution of other cations for Na+ in the incubation mixture significantly affected sulfobromophthalein binding. Heating the membranes increased binding. This was due to an increase in maximal binding capacity of the low-affinity, high-capacity sites. The description of saturable binding sites on hepatocellular surface membranes, the affinity of one of the sites exceeding the reported affinities for albumin and ligandin, supports the hypothesis that a membrane-located membrane carrier is responsible for hepatic uptake and biliary excretion of organic anionic dyes. Based on the studies with enzyme treatments, it is speculated that this carrier is a phospholipid-dependent, integral membrane protein.

Animals↗
PubMed1979

Inhibition of hepatic Na +, K + -adenosinetriphosphatase in taurolithocholate-induced cholestasis in the rat.

Na +, K + -adenosinetriphosphatase (Na +, K + -ATPase) activity was decreased in liver plasma membranes from rats in which cholestasis had been induced by i.v. administration of sodium taurolithocholate (5 mumoles/100 g b. wt). Incubation of liver plasma membranes with taurolithocholate (10--1300 muM) caused significant and dose dependent reductions of Na +, K + -ATPase activity at taurolithocholate concentrations above 100 muM. These findings lend support to the hypothesis that cholestasis induced by monohydroxy bile acids is at least partially the result of an inhibition of hepatic Na +, K + -ATPase activity.

Animals↗
PubMed1979

Cation-anion gap and choleretic properties of rat bile.

To investigate whether bile contains choleretic anion(s) other than bile salts (BS) that could account for the observed cation-anion gap in bile, the choleretic properties of bile were investigated in the rat. Infusion of bile increased bile flow significantly more than did taurocholate (TC) (P less than 0.005). By contrast, TC increased BS excretion more substantially (P less than 0.01). This effect was dose dependent for both bile and TC. The choleretic principle had a molecular weight of less than 1,000 as estimated by ultrafiltration of bile. Infusion of bile that had been chromatographed on BioBeads SM-2 still elicited choleresis, whereas bile that had been chromatographed on Dowex 1 x 50W did not. Administration of bile in vivo did not affect Na+-K+-stimulated ATPase activity in liver plasma membrane fractions. These results suggest that bile contains anion(s) other than 3-hydroxy-BS, which increase bile flow in a dose-dependent fashion without affecting the permeability of the biliary tree. This putative choleretic appears to be anionic in nature, heat stable, and has an apparent molecular weight of less than 1,000. This finding suggested that bile salt-independent bile flow partly depends on the excretion of a currently undefined anion.

Animals↗
PubMed1979

[Hepatic extraction of taurocholate and indocyanine green in patients with liver disease (author's transl)].

Bile acids are increasingly used as test substances for the estimation of liver function and it has been postulated that radioactive labeled bile acids have advantages over indocyanine green (ICG) for measurement of hepatic blood flow. Therefore, the hepatic extractions of 14C-taurocholate and ICG were compared in 23 patients with liver disease and correlated with various parameters of hepatic function. The hepatic extractions of 14C-taurocholate (mean: 42 +/- SD 17%) and ICG (mean: 35 +/- SD 18%) were similar. The correlations with galactose elimination capacity and BSP plasma disappearance were closer for ICG than for 14C-taurocholate extraction. Hepatic blood flow measured with 14C-taurocholate (mean: 1.45 +/- SD 0.51 l/min) correlated well (r = 0.81) with the respective values obtained with ICG (mean: 1.17 +/- SD 0.49 l/min), but was about 22% larger. This study does not provide evidence that 14C-taurocholate is superior to ICG as an intravenous test substance for measurement of hepatic function or blood flow.

Adult↗
PubMed1977

Relationship between bile flow and Na+, K+-adenosinetriphosphatase in liver plasma membranes enriched in bile canaliculi.

The relationship between bile flow and Na+,K+-ATPase activity in liver plasma membranes enriched in bile canaliculi was studied in rats treated with ethinyl estradiol, phenobarbital, or 20-methyl cholanthrene. In comparison with controls (1.49+/-0.12 microliter/min per g liver), bile flow was significantly diminished by ethinyl estradiol, increased by phenobarbital, and unchanged by 20-methyl cholanthrene or the solvent, propanediol (0.92+/-0.31, 2.50+/-0.21, 1.62+/-0.18, and 1.64+/-0.30 microliter/min per g liver, respectively). The corresponding values for canalicular Na+,K+-ATPase activity were 80.7+/-19.2, 50.0+/-18.4, 231.7+/-42.6, 82.7+/-30.7, and 143.6+/-55.3 micronmol Pi/h per g liver. Canalicular Na+,K+-ATPase activity was significantly correlated (r=0.785, n=31) with bile flow. These findings support the hypothesis that a fraction of bile flow is related to Na+,K+-ATPase activity and canalicular Na+ transport.

Adenosine Triphosphatases↗
PubMed1976

Kinetics of hepatic uptake of unconjugated bilirubin.

1. The uptake of bilirubin was studied in the perfused rat liver by a multiple-indicator dilution technique employing the three-compartment model of Goresky. 2. The kinetics of hepatic bilirubin uptake could be described by the Michaelis-Menten equation. 3. The maximal uptake velocity (V max.) and the apparent half-saturation constant (Km) were 4-4 +/- 0-5 nmol s-1 g-1 of liver and 58 +/- 16 nmol/g of liver respectively, indicating that the hepatic uptake system for bilirubin under normal conditions is operating far below saturation. 4. Sodium taurocholate did not compete with bilirubin for hepatic uptake. 5. These findings are consistent with the concept that carrier-mediated transport is responsible for hepatocellular uptake of bilirubin and that bilirubin and bile acids enter the hepatocyte via separate pathways.

Animals↗
PubMed1976

Uptake of bile acids by perfused rat liver.

The uptake of 14C-labeled cholic, taurocholic, and chenodeoxycholic acid by the perfused rat liver was studied to characterize the mechanism responsible for hepatic uptake of bile acids. A rapid-injection multiple indicator-dilution technique and the three-compartment model of Goresky were employed. The kinetics of hepatic uptake of the three bile acids could be described by the Michaelis-Menten equation. The maximal uptake velocities (Vmax) were 24.9 +/- 2.2 (mean +/- SD), 20.8 +/- 1.2, 1.2, and 11.4 +/- 0.9 nmol/s-g liver for cholic, taurocholic, and chenodeoxycholic acid, respectively. The corresponding apparent half-saturation constants (Km) were 526 +/- 125, 258 +/- 43, and 236 +/- 48 nmol/g liver. Competitive inhibition could be demonstrated between cholate and taurocholate as well as between cholate and chenodeoxycholate. Substitution of 94% of the Na+ in the perfusion medium decreased the Vmax and the apparent Km of taurocholate uptake by 68 and 55%, respectively. These findings are consistent with the hypothesis that bile acids are taken up into the hepatocyte by Na+-dependent carrier-mediated transport.

Animals↗