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W Gerok

Publications and source records attributed to W Gerok.

At least 145 records · Page 8Linked to original sources
PubMed1989

Characterization of mononuclear-phagocyte terminal maturation by mRNA phenotyping using a set of cloned cDNA probes.

The terminal step in the maturation of mononuclear cells from circulating monocytes to resident macrophages is accompanied by dramatic changes in cell morphology and physiology. Applying a cultivation system which allows peripheral monocytes to undergo terminal maturation in vitro under absolutely endotoxin-free conditions, we have determined the pattern of expression of a set of eight genes by mRNA phenotyping. The results can be summarized as follows: the two protease inhibitors alpha 1-antitrypsin and alpha 2-macroglobulin show a inverse pattern of expression. alpha 1-Antitrypsin mRNA is repressed, alpha 2-macroglobulin mRNA is strongly induced during maturation to macrophages. Therefore, these two genes are excellent markers of the terminal maturation. In addition, ferritin-light-chain mRNA progressively increases during the course of differentiation, providing a further marker for maturation. Gene expression as a function of activation was studied in mononuclear cells stimulated with bacterial endotoxin (lipopolysaccharide). In monocytes, complement-factor-B, interleukin-1 and interleukin-6 mRNAs are drastically induced upon lipopolysaccharide activation whereas lysozyme RNA is strongly repressed. However, the ability of all four genes to respond to endotoxin was markedly diminished or abolished in mature macrophages, indicating that susceptibility to a certain type of activation may be restricted to a specific stage of maturation. Our data show that mRNA phenotyping is excellently suited for the characterization of the differentiation and activation state of mononuclear phagocytes.

Blotting, Northern↗
PubMed1989

Regulation of interleukin 6 receptor expression in human monocytes and monocyte-derived macrophages. Comparison with the expression in human hepatocytes.

IL-6 is a cytokine with pleiotropic biological functions, including induction of the hepatic acute phase response and differentiation of activated B cells into Ig-secreting plasma cells. We found that human peripheral blood monocytes express the IL-6-R, which is undetectable on the large majority of lymphocytes of healthy individuals. Stimulation of monocytes by endotoxin or IL-1 causes a rapid downregulation of IL-6-R mRNA levels and a concomitant enhancement of IL-6 mRNA expression. IL-6 itself was found to suppress the IL-6-R at high concentrations. A gradual decrease of IL-6-R mRNA levels was observed along in vitro maturation of monocytes into macrophages. We show that downregulation of IL-6-R mRNA levels by IL-1 and IL-6 is monocyte specific, since IL-6-R expression is stimulated by both IL-1 and IL-6 in cultured human primary hepatocytes. Our data indicate that under noninflammatory conditions, monocytes may play a role in binding of trace amounts of circulating IL-6. Repression of monocytic IL-6-R and stimulation of hepatocytic IL-6-R synthesis may represent a shift of the IL-6 tissue targets under inflammatory conditions.

Blotting, Northern↗
PubMed1989

Hepatocyte heterogeneity in glutamate metabolism and bidirectional transport in perfused rat liver.

1. The metabolic fate of infused [1-14C]glutamate was studied in perfused rat liver. The 14C label taken up by the liver was recovered to 85 +/- 2% as 14CO2 and [14C]glutamine. Whereas 14CO2 production accounted for about 70% of the [1-14C]glutamate taken up under conditions of low endogenous rates of glutamine synthesis, stepwise stimulation of glutamine synthesis by NH4Cl increased 14C incorporation into glutamine at the expense of 14CO2 production. Extrapolation to maximal rates of hepatic glutamine synthesis yielded an about 100% utilization of vascular glutamate taken up by the liver for glutamine synthesis. This was observed in both, antegrade and retrograde perfusions and suggests an almost exclusive uptake of glutamate into perivenous glutamine-synthetase-containing hepatocytes. 2. Glutamate was simultaneously taken up and released from perfused rat liver. At a near-physiological influent glutamate concentration (0.1 mM), the rates of unidirectional glutamate influx and efflux were similar (about 100 and 120 nmol g-1 min-1, respectively). 3. During infusion of [1-14C]oxoglutarate (50 microM), addition of glutamate (2 mM) did not affect hepatic uptake of [1-14C]oxoglutarate. However, it increased labeled glutamate release from the liver about 10-fold (from 9 +/- 2 to 86 +/- 20 nmol g-1 min-1; n = 4), whereas 14CO2 production from labeled oxoglutarate decreased by about 40%. This suggests not only different mechanisms of oxoglutarate and glutamate transport across the plasma membrane, but also points to a glutamate/glutamate exchange. 4. Oxoglutarate was recently shown to be taken up almost exclusively by perivenous glutamine-synthetase-containing hepatocytes [Stoll, B & Häussinger, D. (1989) Eur. J. Biochem. 181, 709-716] and [1-14C]oxoglutarate (9 microM) was used to label selectively the intracellular glutamate pool in this perivenous cell population. The specific radioactivity of this intracellular (perivenous) glutamate pool was assessed by measuring the specific radioactivity of newly synthesized glutamine which is continuously released from these cells into the perfusate. Comparison of the specific radioactivities of glutamine and glutamate released from perivenous cells indicates that about 60% of total glutamate release from the liver is derived from the perivenous glutamine-synthetase-containing cell population. Following addition of unlabeled glutamate (0.1 mM), unidirectional glutamate efflux from perivenous cells increased from about 30 to 80 nmol g-1 min-1, whereas glutamate efflux from non-perivenous (presumably periportal) hepatocytes remained largely unaltered (i.e. 20-30 nmol g-1 min-1). 5. It is concluded that, in the intact liver, vascular glutamate is almost exclusively taken up by the small perivenous hepatocyte population containing glutamine synthetase.

Animals↗
PubMed1989

[The intrahepatic portosystemic shunt. Initial clinical experiences with patients with liver cirrhosis].

A new nonoperative catheter technique to perform an intrahepatic portosystemic shunt by transjugular approach was applied to ten patients with recurrent bleeding from oesophageal and fundal varices. Therefore a balloon-expandable stent was placed between a portal vein and a hepatic vein. Implantation of the stent was successful in seven of the ten patients. Two of these seven patients died 10 and 11 days, respectively, after the procedure, one of them in consequence of respiratory failure, the other due to an uncontrollable bleeding from the site of the percutaneous transhepatic puncture because of a marked clotting disorder. The intrahepatic shunt construction led to a mean reduction of the pressure gradient between portal and hepatic vein of 40%. No recurrence of variceal haemorrhage occurred during the average follow-up time of 5.6 months (3-9 months). One patient developed several episodes of portosystemic encephalopathy. The transjugular intrahepatic portosystemic shunt is effective in the treatment of portal hypertension and might become an alternative to shunt surgery.

Adult↗
PubMed1989

Effect of the alpha-glucosidase inhibitor N-hydroxyethyl-1-deoxynojirimycin (Bay m 1099) on the biosynthesis of liver secretory glycoproteins.

The effect of the alpha-glucosidase inhibitor N-hydroxyethyl-1-deoxynojirimycin (Bay m 1099) on the glycosylation and secretion of alpha 1-antitrypsin (three complex type oligosaccharide chains) and of alpha 1-acid glycoprotein (six complex type oligosaccharide chains) was studied in rat hepatocyte primary cultures. In the presence of 4 mM Bay m 1099 the processing of high-mannose to complex type oligosaccharides was partially inhibited leading to the secretion of alpha 1-antitrypsin and alpha 1-acid glycoprotein carrying a mixture of both high-mannose and complex type oligosaccharides. The major part of alpha 1-antitrypsin secreted by Bay m 1099 treated cells still carried two complex type oligosaccharide chains, the majority of alpha 1-acid glycoprotein carried three to five. Despite its effects on protein glycosylation Bay m 1099 did not lead to pronounced changes in the synthesis or secretion of alpha 1-antitrypsin, alpha 1-acid glycoprotein or albumin. At concentrations of Bay m 1099 lower than 0.5 mM no inhibitory effect on oligosaccharide trimming could be observed. After removal of Bay m 1099 from hepatocytes its inhibitory effect on protein glycosylation was immediately reversible.

1-Deoxynojirimycin↗
PubMed1989

Regulation of interleukin-6 receptor expression in human monocytes and hepatocytes.

Human blood monocytes normally express the interleukin-6 receptor. Treatment of cultured monocytes with endotoxin, interleukin-1 beta, or interleukin-6 results in a decrease in interleukin-6 receptor mRNA levels. Glucocorticoids aso cause a drop in monocytic interleukin-6 receptor mRNA levels. We also found interleukin-6 receptor expression in cultured human hepatocytes, but in contrast to monocytes, where interleukin-6 receptor mRNA is presented by the ligand and by interleukin-1, treatment of hepatocytes with interleukin-6 or interleukin-1 resulted in increased interleukin-6 receptor mRNA levels. Induction of interleukin-6 receptor mRNA in hepatocytes was less pronounced when glucocorticoids were omitted from the culture medium. We conclude that during noninflammatory homeostasis, blood monocytes are involved in binding of trace amounts of circulating interleukin-6. During inflammatory events, the main target of interleukin-6 may be changed from the monocytic population not only to activated B-cells, but also to the hepatocytes.

Acute-Phase Reaction↗
PubMed1989

Gangliosides in normal human serum. Concentration, pattern and transport by lipoproteins.

The total content and pattern of gangliosides were determined in the unfractionated sera of 11 healthy human adults and in isolated lipoproteins. The total content of lipid-bound sialic acid was 10.5 +/- 3.2 nmol/ml serum. The ganglioside profile consisted of more than ten different components. The major ganglioside was GM3, followed by GD3, GD1a, GM2, GT1b, MG-3 (sialosyllactoneotetraosylceramide), GD1b and GQ1b. Traces of four additional gangliosides could not be quantified reliably. Ganglioside patterns did not vary in sera taken from healthy adults of different age and sex. Approximately 98% of human serum gangliosides were transported by serum lipoproteins, predominantly by LDL (66%), followed by HDL (25%) and VLDL (7%). The quantitative distribution of individual gangliosides in VLDL and LDL was almost the same as that in the unfractionated serum; some differences existed with the ganglioside profile in HDL.

Adult↗
PubMed1989

O- and N-glycosylation lead to different molecular mass forms of human monocyte interleukin-6.

The biosynthesis and secretion of human interleukin-6 (IL-6) was studied in monocyte cultures stimulated with endotoxin. After labeling with [35S]methionine and immunoprecipitation with a specific antiserum one major (24 kDa) and four minor (27.5, 23.3, 22.5 and 21.8 kDa) molecular mass forms of IL-6 could be found in the cells and media. Incubation of monocyte media with sialidase and subsequently with endo-alpha-N-acetylgalactosaminidase, which cleaves Gal(beta 1-3)Gal-NAc from serine or threonine, led to the formation of only two forms of IL-6 with apparent molecular masses of 25 and 21.8 kDa. The latter had an electrophoretic mobility indistinguishable from that of 125I-labeled recombinant human IL-6. The results suggest that human monocyte IL-6 carries O-glycosidically bound carbohydrates with a Gal(beta 1-3)Gal-NAc core to which only sialic acid is bound. Differences in O-glycosylation are the major cause for the molecular heterogeneity of IL-6. A small part of IL-6 (27.5 kDa form) is in addition N-glycosylated. Incubation of monocytes with tunicamycin and 1-deoxymynnojirimycin and treatment of IL-6 with endoglucosaminidase H suggested that the 27.5 kDa form of IL-6 carries at least one N-linked complex-type oligosaccharide chain.

1-Deoxynojirimycin↗
PubMed1989

Metabolism of cysteinyl leukotrienes in non-recirculating rat liver perfusion. Hepatocyte heterogeneity in uptake and biliary excretion.

1. The uptake, metabolism and biliary excretion of the cysteinyl leukotrienes LTC4, LTD4 and LTE4, were studied in a non-recirculating rat liver perfusion system at constant flow in both antegrade (from the portal to the caval vein) and retrograde (from the caval to the portal vein) perfusion directions. During a 5-min infusion of [3H]LTC4, [3H]LTD4 and [3H]LTE4 (10 nmol/l each) in antegrade perfusions single-pass extractions of radioactivity from the perfusate were 66%, 81% and 83%, respectively. Corresponding values for LTC4 and LTD4 in retrograde perfusions were 83% and 93%, respectively, indicating a more efficient uptake of cysteinyl leukotrienes in retrograde than in antegrade perfusions. The concentrations of unmetabolized leukotrienes in the effluent perfusate were 8-12% in antegrade and 2-4% in retrograde perfusions. [14C]Taurocholate extraction from the perfusate was inhibited by LTC4 by only 3%, suggesting that an opening of portal-venous/hepatic-venous shunts does not explain the effects of perfusion direction on hepatic LTC4 uptake. 2. Following infusion of [3H]LTC4 and [3H]LTD4, in the antegrade perfusion direction, about 80% and 87%, respectively, of the radiolabel taken up by the liver was excreted into bile. In retrograde perfusions, however, only 40% and 57%, respectively, was excreted into bile and the remainder was slowly redistributed into the perfusate, indicating that leukotrienes were taken up into a hepatic compartment with less effective biliary elimination or converted to metabolites escaping biliary excretion. The metabolite pattern found in bile was not affected by the direction of perfusion. Biliary products of LTC4 were polar metabolites (31-38%), LTD4 (27-30%), LTE4 (about 1%) and N-acetyl-LTE4 (3-4%) in addition to unmodified LTC4 (17-18%). 3. LTC4 was identified as a major metabolite of [3H]LTD4 in bile, amounting to about 20% of the total radioactivity excreted into bile. This is probably due to a gamma-glutamyltransferase-catalyzed glutamyl transfer from glutathione in the biliary compartment, as demonstrated in in vitro experiments. The presence of sinusoidal gamma-glutamyltransferase activity in perfused rat liver was shown in experiments on the hydrolysis of infused gamma-glutamyl-p-nitroanilide. 90% inhibition of this enzyme activity by AT-125 did not affect the metabolism of LTC4. 4. When [3H]LTE4 was infused in the antegrade perfusion direction, biliary metabolites comprised N-acetyl-LTE4 (24%) and polar components (60%).(ABSTRACT TRUNCATED AT 400 WORDS)

Aniline Compounds↗
PubMed1989

[Ambulatory sonography in clinical and general practice. Incidence and accuracy of findings and consequences].

In a prospective study an ultrasound examination was performed in 372 out-patients. 230 were examined in two physicians offices (group I) and 142 in a clinical ultrasound center (group II). The indication for ultrasound was different in both groups: 42% of patients in group I were examined without exact questions. Search for primary tumors or metastasis were more often indications in group II. More patients were found to have liver abnormalities and less biliary disease in group II. The impact of ultrasound findings on final diagnosis was not different. More diagnostic and therapeutic consequences resulted in group I, in particular in patients with cholelithiasis. A broad indication for sonography in the physicians office is justified given sufficient experience of the examiner. With respect to the consequences of the findings improvement is warranted.

Abdominal Neoplasms↗
PubMed1989

[Hypophosphatemic osteomalacia in adults].

Hypophosphataemic osteomalacia occurred in a 38-year-old woman. The leading clinical symptom was severe bone pain. X-ray studies demonstrated fractures of the iliac crest and pubic and ischiadic bone, as well as Looser's zones and demineralization of the skeleton. Computerized densitometry of the bone revealed a 31% reduction of hydroxyapatite. Histological evaluation showed nearly absence of osteoclasts and extensive demineralisation of the bone. Hypophosphataemia (0.48 mmol/l), increased urinary phosphate clearance (36 ml/min), reduced renal-tubular reabsorption for phosphate (73%) and increased alkaline phosphatase (355 U/l) were present. Parathyroid hormone and 1,25-dihydroxyvitamin D were normal. No inborn errors, disturbances of the calcium metabolism or paraneoplastic signs could be detected. Defective renal tubular reabsorption of phosphate is likely to be the underlying cause of the disease. Phosphate supplementation and intermittent vitamin D administration remains the therapy of choice.

Adult↗
PubMed1989

Regulation of hepatic parenchymal and non-parenchymal cell function by the diadenine nucleotides Ap3A and Ap4A.

The diadenine nucleotides diadenosine 5',5"-P1,P3-triphosphate (Ap3A) and diadenosine 5',5"-P1,P4-tetraphosphate (Ap4A) can be released from platelets and were shown to act as long-lived signal molecules. Accordingly, we studied their potential effect on hepatic metabolism. In isolated perfused rat liver, Ap3A and Ap4A increase the portal pressure, lead to a transient net release of Ca2+, complex net K+ movement across the liver plasma membrane and stimulate hepatic glucose output and 14CO2 production from [1-14C]glutamate. These responses resemble that obtained with extracellular ATP. This and studies on the additivity of ATP and Ap4A effects suggest similar mechanisms mediating the ATP and diadenine nucleotide effects in the liver. Ap3A and Ap4A increased the activity of glycogen phosphorylase a in isolated hepatocyte suspensions by about 100%, pointing to a direct effect of these nucleotides on hepatic parenchymal cells. A response of hepatic non-parenchymal cells to diadenine nucleotide infusion is suggested by a marked stimulation of thromboxane and prostaglandin D2 release from perfused liver. Studies with the thromboxane A2 receptor antagonist BM 13.177 (20 microM) show that the pressure and glucose response to the diadenine nucleotides is partially mediated by this thromboxane formation. Studies with retrograde and sequential liver perfusions suggest a less efficient degradation of the diadenine nucleotides during a single liver passage compared to extracellular ATP. The data suggest that Ap3A and Ap4A are potential regulators of hepatic hemodynamics and metabolism, involving complex interactions between hepatic parenchymal cells and hepatic non-parenchymal cells, including eicosanoids as signal molecules.

Animals↗
PubMed1989

Correlation of caffeine elimination and Child's classification in liver cirrhosis.

Apparent pharmacokinetic parameters of caffeine elimination from the circulation were determined in 27 patients with histologically confirmed liver cirrhosis, 8 patients with miscellaneous liver disease, and 8 patients with other than liver disease. The usefullness of this quantitative test to assess the severity of liver cirrhosis was compared to the Child-Turcotte or Child-Pugh classification score as well as to the galactose elimination capacity of these patients. Using reversed-phase high pressure liquid chromatography caffeine, paraxanthine, theophylline, and theobromine were analysed in blood plasma collected before and after an oral dose of caffeine. Compared to apparent caffeine pharmacokinetics in patients with normal livers or miscellaneous liver disease, cirrhosis was characterized by a statistically significant reduction in apparent caffeine clearance and prolongation in half-life. The reduced apparent plasma disappearance rate of caffeine in cirrhotics was related to the retarded formation of paraxanthine which was the main metabolite of caffeine in blood plasma both in the absence or presence of liver disease. The apparent caffeine clearance in cirrhosis decreased with increasing Child-Turcotte classification score: Child's class A patients differed significantly from Child's class B or Child's class C patients, whereas the difference between Child's class B and C patients did not reach statistical significance (Wilcoxon's rank test). In addition there was a strong correlation between the Child-Pugh classification score and apparent caffeine clearance (P less than 0.001). However, no correlation existed between Child's classification and galactose elimination capacity. Our data emphasize the value of the Child-Turcotte or Child-Pugh classification in assessing the severity of liver cirrhosis in a simpler and less time-consuming way than using quantitative liver function tests.

Administration, Oral↗
PubMed1989

The role of nonparenchymal and parenchymal liver cells in the catabolism of extracellular purines.

Adenosine-degrading enzymes within the liver lobule can modulate both vascular and metabolic effects of circulating adenosine in the liver. Since it has not been fully established whether nonparenchymal cells participate in the elimination of sinusoidal purines, isolated Kupffer cells and endothelial cells were tested for their capacity to degrade extracellular purines. After perfusion and digestion of rat livers by collagenase, the resulting mixed cell population was separated by centrifugal elutriation. The isolated parenchymal and nonparenchymal cells were incubated for up to 2 hr in the presence of [8(-14)C]adenosine, [8(-14)C]guanosine and [8(-14)C]hypoxanthine (50 mumoles per liter). In the deproteinized medium, adenosine, guanosine, inosine, adenine, guanine, xanthine, hypoxanthine, uric acid and allantoin were separated by reversed-phase high-performance liquid chromatography. Radioactive peaks were collected and counted. Nonparenchymal cells catalyzed the degradation of adenosine into inosine and hypoxanthine. However, the formation of xanthine, uric acid or allantoin from adenosine could only be detected in hepatocyte suspensions. Within 15 min, adenosine was completely eliminated from the medium by Kupffer cells, whereas endothelial cells catabolized only less than half of the initial amount of the adenine nucleoside during this time period. Accordingly, incubation of nonparenchymal cells in the presence of hypoxanthine did not result in the formation of further breakdown products of the purine, whereas its catabolites slowly accumulated in the medium of hepatocytes. Guanosine conversion into guanine and xanthine was much slower in endothelial cells as compared to Kupffer cells and hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1989

Detection of biliary origin of acute pancreatitis. Comparison of laboratory tests, ultrasound, computed tomography, and ERCP.

Fifty consecutive patients with acute pancreatitis were assessed with respect to a biliary origin of the disease. Endoscopic retrograde cholangiopancreaticography, surgery, and autopsy were used to define biliary pancreatitis. Ultrasound, computed tomography, and several laboratory tests (SGOT, SGPT, alkaline phosphatase, and bilirubin) were analyzed for their ability to detect a biliary origin of the disease. Ultrasound and computed tomography could not reliably make the diagnosis in the 10 patients found to have biliary disease. Receiver-operator-characteristic curves revealed that none of the laboratory tests assessed had sufficient sensitivity and specificity to determine the diagnosis, although all tests showed higher mean values in biliary pancreatitis. SGPT gave the best discrimination (positive predictive value 53%, negative predictive value 94%, cut off 40 units/liter). Therefore, initial ERCP is suggested for a reliable diagnosis of biliary origin of acute pancreatitis.

Acute Disease↗
PubMed1989

Relapsing pancreatitis as initial manifestation of cystic fibrosis in a young man without pulmonary disease.

In young adults with acute pancreatitis a wide etiologic spectrum has to be considered. Among the possible causes, cystic fibrosis is rare. Besides the typical clinical triad of pancreatic exocrine insufficiency, chronic obstructive pulmonary disease, and elevated sweat chloride levels, there is a wide spectrum of variants of the cystic fibrosis syndrome. Especially mild manifestations of the disease may, therefore, escape proper identification. Here we describe a young man who presented initially with recurrent acute pancreatitis without pulmonary disease and without a family history of cystic fibrosis, in whom the diagnosis of cystic fibrosis was established by slightly elevated sweat chloride levels and obstructive azoospermia. Five years after the first attack of pancreatitis the patient developed pancreatic exocrine insufficiency.

Adult↗