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Biomedical subjects

U Gärtner

Publications and source records attributed to U Gärtner.

At least 55 records · Page 3Linked to original sources
PubMed1989

Plasma clearance of bile acids in the rat: hepatic uptake under physiological conditions without countertransport.

Studies in rats by others indicated that sulfobromophthalein (BSP), bilirubin and indocyanine green are taken up by the liver and can be transported back to plasma against the prevailing concentration gradient (= countertransport). The present in vivo study was designed to determine whether the bile acids cholic acid and taurocholic acid under physiological conditions undergo appreciable countertransport as has been suggested by experiments in isolated hepatocytes. Experiments with BSP (controls) showed that injections of unlabeled BSP into rats five minutes after the administration of radiolabeled BSP was followed by a release of radioactivity into plasma (BSP-countertransport). In contrast bile acid countertransport could not be demonstrated, no matter whether it was tested 1, 5 or 8 minutes after the administration of radiolabeled cholic- or taurocholic acid.

Animals↗
PubMed1983

Hepatic bilirubin uptake in the isolated perfused rat liver is not facilitated by albumin binding.

Bilirubin uptake by the liver is a rapid process of high specificity that has kinetic characteristics which suggest carrier-mediation. In the circulation, bilirubin is readily bound to albumin, from which it is extracted by the liver. Although several studies suggested that it is the small, unbound fraction of bilirubin which interacts with hepatocytes and is removed from the circulation, recent experiments have been interpreted as suggesting that binding to albumin facilitates ligand uptake. A liver cell surface receptor for albumin has been postulated. The present study was designed to examine directly whether albumin facilitates the hepatic uptake of bilirubin and whether uptake of bilirubin depends on binding to albumin. Rat liver was perfused with a protein-free fluorocarbon medium, and single-pass uptake of 1, 10, or 200 nmol of [3H]bilirubin was determined after injection as an equimolar complex with 125I-albumin, with 125I-ligandin, or free with only a [14C]sucrose reference. Uptake of 10 nmol of [3H]bilirubin was 67.5 +/- 3.7% of the dose when injected with 125I-albumin, 67.4 +/- 6.5% when injected with 125I-ligandin, and 74.9 +/- 2.4% when injected with [14C]sucrose (P greater than 0.1). At 200 nmol, uptake fell to 46.4 +/- 3.1% (125I-albumin) and 63.3 +/- 3.4% [( 14C]sucrose) of injected [3H]bilirubin (P less than 0.01), which suggests saturation of the uptake mechanism. When influx was quantitated by the model of Goresky, similar results were obtained. When [3H]bilirubin was injected simultaneously with equimolar 125I-albumin and a [14C]sucrose reference, there was no delay in 125I-albumin transit as compared with that of [14C]sucrose. This suggested that the off-rate of albumin from a putative hepatocyte receptor would have to be very rapid, which is unusual for high affinity receptor-ligand interaction. There was no evidence for facilitation of bilirubin uptake by binding to albumin or for interaction of albumin with a liver cell surface receptor. These results suggest that the hepatic bilirubin uptake mechanism is one of high affinity which can extract bilirubin from circulating carriers such as albumin, ligandin, or fluorocarbon.

Animals↗
PubMed1983

Branched-chain amino acid-enriched elemental diet in patients with cirrhosis of the liver. A double blind crossover trial.

In 14 patients with cirrhosis of the liver and portal-systemic shunts the effect of a branched-chain amino acid-enriched elemental diet on portal systemic encephalopathy, routine laboratory parameters and plasma amino acids was investigated. In addition to the standard therapy including protein restriction (40 g/day) the patients received 44 g of an amino acid-protein mixture containing 30% of branched-chain amino acids and placebo over 3 months in a crossover regimen. Plasma valine and leucine increased significantly, whereas all other amino acids, including the ratio (formula: see text), remained unchanged. The electroencephalogram, number connection test, clinical state and laboratory parameters were not influenced by therapy with branched-chain amino acids. Thus, orally administered branched-chain amino acids probably have no influence on hepatic encephalopathy but are an adequate source of nitrogen in patients with cirrhosis of the liver.

Adult↗
PubMed1982

Bilirubin diglucuronide formation in intact rats and in isolated Gunn rat liver.

Bilirubin diglucuronide (BDG) may be formed in vitro by microsomal UDP glucuronosyl transferase (EC 2.4.1.17)-mediated transfer of a second mole of glucuronic acid from UDP-glucuronic acid, or by dismutation of bilirubin monoglucuronide (BMG) to BDG and unconjugated bilirubin, catalyzed by an enzyme (EC 2.4.1.95) that is concentrated in plasma membrane-enriched fractions of rat liver. To evaluate the role of these two enzymatic mechanisms in vivo, [(3)H]bilirubin mono-[(14)C]glucuronide was biosynthesized, purified by thin-layer chromatography, and tracer doses were infused intravenously in homozygous Gunn (UDP glucuronyl transferase-deficient) rats or Wistar rats. Bilirubin conjugates in bile were separated by high-pressure liquid chromatography and (3)H and (14)C were quantitated. In Gunn rats, the (14)C:(3)H ratio in BDG excreted in bile was twice the ratio in injected BMG. In Wistar rats the (14)C:(3)H ratio in biliary BDG was 1.25 +/- 0.06 (mean +/- SEM) times the ratio in injected BMG. When double labeled BMG was injected in Wistar rats after injection of excess unlabeled unconjugated bilirubin (1.7 mumol), the (14)C:(3)H ratio in BDG excreted in bile was identical to the ratio in injected BMG. Analysis of isomeric composition of bilirubin conjugates after alkaline hydrolysis or alkaline methanolysis indicated that the bile pigments retained the IX(alpha) configuration during these experiments. The results indicate that both enzymatic dismutation and UDP glucuronyl transferase function in vivo in BDG formation, and that dismutation is inhibited by a high intrahepatic concentration of unconjugated bilirubin. This hypothesis was supported by infusion of [(3)H]bilirubin-monoglucuronide in isolated perfused homozygous Gunn rat liver after depletion of intrahepatic bilirubin by perfusion with bovine serum albumin (2.5%), and after bilirubin repletion following perfusion with 0.34 mM bilirubin. From 20 to 25% of injected radioactivity was recovered in BDG in bile in the bilirubin-depleted state; only 8-10% of radioactivity was in BDG in bile after bilirubin repletion. After infusion of [(3)H]bilirubin di-[(14)C]glucuronide in homozygous Gunn rats, 5-7% of the injected pigment was excreted in bile as BMG. The (14)C:(3)H ratio in the injected BDG was 10% greater than the (14)C:(3)H ratio in BMG excreted in bile. These results indicate that in vivo, dismutation rather than partial hydrolysis, is responsible for BMG formation. Incubation of [(3)H]bilirubin, BDG and a rat liver plasma membrane preparation resulted in formation of BMG (3.3 nmol/min per mg protein) indicating that dismutation is also reversible in vitro.

Animals↗
PubMed1982

Effect of nafenopin on the uptake of bilirubin and sulfobromophthalein by isolated perfused rat liver.

Hepatic uptake of bilirubin and sulfobromophthalein has kinetic characteristics suggesting facilitated diffusion. Because these compounds demonstrate mutual competition for uptake, a shared uptake mechanism has been presumed. Previous studies in isolated perfused regenerating liver revealed depressed uptake of bilirubin, sulfobromophthalein, and asialoorosomucoid, a desialylated glycoprotein which enters hepatocytes by receptor-mediated endocytosis. This study was designed to determine whether or not depressed transport seen in liver regeneration occurs in other states of hepatocellular proliferation. Rats were pretreated with nafenopin (200 mg/kg . day x 2), a drug that causes rapid hepatocellular proliferation similar to that seen in regeneration. Twenty-four hours after nafenopin treatment, liver weight increased by 40%. Influx, efflux, and sequestration rate constants in isolated perfused liver were quantitated by a computer fit to the model of Goresky. Results 1 day after nafenopin treatment revealed no change in transport parameters for bilirubin and asialoorosomucoid, but 55% and 49% reductions in influx of sulfobromophthalein and conjugated bilirubin, respectively. These studies suggest that hepatocellular proliferation alone is not responsible for the transport alterations seen during liver regeneration. Nafenopin effectively unmasks differences in uptake of bilirubin and other more water soluble organic anions such as sulfobromophthalein and conjugated bilirubin, suggesting that their uptake mechanisms are partially independent.

Animals↗
PubMed1980

Effects of receptor-specific antibody on the uptake of desialylated glycoproteins in the isolated perfused rat liver.

Removal of the terminal sialic acid residues from most mammalian glycoproteins results in their rapid transfer from the circulation into the liver. In vitro, these desialylated glycoproteins bind to a specific membrane-associated hepatic lectin which has a ubiquitous distribution within the liver cell. In the present study, infusion of a specific antibody to the purified lectin into the portal vein of an isolated perfused rat liver prior to injection of radiolabeled asialoorosomucoid or bilirubin reduced the rate of influx of asialoorosomucoid into the liver by over 80%, while the influx of bilirubin was unchanged. Although uptake of asialoorosomucoid remained blocked for at least 90 min after excess antibody was removed from the perfusion system, the total hepatic content of functional binding protein was nearly normal. These results indicate that interaction with specific cell surface lectin is essential for removal of asialoorosomucoid from the circulation. During the 90 min following infusion of antibody, no functional lectin is restored to the surface of hepatocytes.

Animals↗
PubMed1979

[Pacemaker's twiddler syndrome (author's transl)].

This report demonstrates the results of five observation of the Pacemaker's-twiddler-syndrome, which will not necessarily end in the complete malfunction of the pacemaker unit. Therefore we classify the Pacemaker's-twiddler-syndrome as a partial and a complete form. The partial form is characterized by still effective cardiac stimulation, whereas the complete form can not stimulate the heart muscle because of the retracted electrode. Also methods of early detection and prevention of the Pacemaker's-twiddler-syndrome are discussed.

Aged↗
PubMed1978

[Atypical paraproteinemic hemoblastoses (author's transl)].

The symptomatology of typical paraproteinemic hemoblastoses (plasma cell myeloma, Wadenström's macroglobulinemia) are well known. Once suspected, diagnosis of these disorders can easily be established in the majority of cases. Differentiation of benign paraproteinemias requiring no treatment is likewise possible by careful observation of the course of disease and relevant clinical criteria. Very seldom, cases of paraproteinemic hemoblastoses are seen which differ from the usual immunoelectrophoretic analysis and clinical picture. Two very unusual cases of paraproteinemia are presented.

Adenocarcinoma↗
PubMed1977

[Emergency endoscopy: its application in the department of medicine of a city hospital (author's transl)].

In about 90% of cases of active gastrointestinal hemorrage, sources and nature of bleeding can be identified exactly by means of emergency endoscopy. With time passing from the beginning of hemorrhage, diagnosis established by endoscopy is getting less precise. The most common cases of bleeding are peptic lesions, either esophageal, gastric, or duodenal; the most common site of hemorrhage is the stomach. Different potential points bleeding at the same time have to be take in account. A case report of Mallory-Weiss syndrome (13 episodes of hemorrhage) illustrated the method's value in establishing diagnosis of acute gastrointestinal bleeding. Special applications of emergency endoscopy in mental patients are described.

Emergencies↗
PubMed1977

[Acquired isolated ventricular septal defects].

Among the acquired defects of ventricular septum the rupture of the septum are known to occur as a rare complication following penetrating and non-penetrating injuries of the chest and more common as sequel of myocardial infarction. A left to right shunt usually follows the acute rupture of the interventricular septum, and is usually lethal. Only a few patients survive for several months under conventional therapy. Early diagnostic procedures using heart catheterization are crucial to determine whether surgical maneuvers are necessary. We present patients who experienced acute rupture of the ventricular septum. We discuss their pathological and clinical findings as well as the problems related to prognosis and therapy.

Accidents↗
PubMed1977

Endoscopic retrograde cholangiopancreaticography (ERCP) in obstructive jaundice caused by metstatic testicular teratoma.

A 28-years-old patient with a palpable mass of two fist's size in the upper abdomen rapidly developed an obstructive jaundice. A pancreatic tumor was suspected and therefore ERCP was carried out. Unusual alterations caused by metastatic lesions of a post mortem diagnosed testicular teratoma narrowing and invading the common bile duct and displacing the main pancreatic duct were visualized.

Abdominal Neoplasms↗