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S Matern

Publications and source records attributed to S Matern.

At least 91 records · Page 5Linked to original sources
PubMed1994

The major metabolites of ursodeoxycholic acid in human urine are conjugated with N-acetylglucosamine.

Ursodeoxycholic acid (750 mg/day) was administered orally to ten healthy subjects over a period of 10 days; 24 hr urine samples were collected the day before and on the last day of the study. Urinary bile acids were extracted, separated into groups of conjugates and analyzed by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry. Excretion of ursodeoxycholic acid rose from 70 to 2,915 micrograms/24 h. The highest increase was observed among N-acetylglucosamine conjugates, 90% of which constituted the previously unknown double conjugate of ursodeoxycholic acid with N-acetylglucosamine and glycine. Excretion of isoursodeoxycholic acid increased from 50 to 738 micrograms/24 h. This isomerization product of ursodeoxycholic acid was excreted almost exclusively as N-acetylglucosamine conjugate. In total, N-acetylglucosamine conjugates constituted 50% of urinary metabolites of ursodeoxycholic acid. In addition, metabolites of ursodeoxycholic acid hydroxylated at carbon atoms 1, 6, 22 and possibly 21 were observed. These compounds were also found as conjugates with N-acetylglucosamine. Their formation from ursodeoxycholic acid was definitely demonstrated by 13C-labeling after giving [24-13C]ursodeoxycholic acid to one of the healthy subjects and to a patient with extrahepatic cholestasis in whom hydroxylation of ursodeoxycholic acid at C-23 was also observed. The patient was also found to excrete the double conjugate of ursodeoxycholic acid with N-acetylglucosamine and taurine. The N-acetylglucosaminidation of ursodeoxycholic acid in vivo was shown to occur at C-7.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosamine↗
PubMed1994

Radioassay of UDP-glucuronosyltransferase activities toward endogenous substrates using labeled UDP-glucuronic acid and an organic solvent extraction procedure.

A rapid and sensitive radioassay for measuring UDP-glucuronosyltransferase activities (EC 2.4.1.17) toward the major endogenous substrates hyodeoxycholic and hyocholic acids, bilirubin, estriol, androsterone, and testosterone has been developed. In this assay, 14C-labeled glucuronides are formed from the enzyme-catalyzed reaction of 14C-labeled UDP-glucuronic acid with the unlabeled aglycones. Following incubation, the 14C-labeled glucuronides are separated under acidic conditions from the unreacted 14C-labeled UDP-glucuronic acid by a single extraction with ethyl acetate. The recovery of glucuronides into ethyl acetate was greater than 90%, whereas the carryover of unreacted UDP-glucuronic acid into the organic phase was approximately 0.2%. The reaction products extracted into ethyl acetate were characterized by their mobilities in thin-layer chromatography and identified as glucuronides by their sensitivity to hydrolysis with beta-glucuronidase and inhibition of hydrolysis by the specific beta-glucuronidase inhibitor D-saccharic acid-1,4-lactone. The optimal conditions of enzyme reactions with the individual aglycones have been defined with human liver microsomes as enzyme source. For all aglycones investigated, 10-30 micrograms of microsomal protein are sufficient for enzyme estimation. The assay is applicable to biochemical studies of UDP-glucuronosyltransferases, as well as to measurement of these enzyme activities from small amounts of clinical liver specimens.

Autoradiography↗
PubMed1994

The submicrosomal localization of uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase and bile acid glucosyltransferase in the human liver.

Uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase and bile acid glucosyltransferase were quantitatively determined in subcellular fractions obtained by differential centrifugation of human liver homogenate. Both enzymes were exclusively enriched in the microsomal fraction with a recovery of total enzyme activity of 65.9 +/- 9.9% and 69.1 +/- 13.8%, respectively. Microsomal preparations were further subfractionated by isopycnic centrifugation on a continuous sucrose density gradient. Both glucosyltransferases closely followed marker constituents of endoplasmic reticulum, as shown by similar distribution profiles in the gradient, but differed in their quantitative distribution among the endoplasmic reticulum membranes. The bile acid glucosyltransferase showed an almost identical distribution with NADPH-cytochrome c reductase as marker of smooth endoplasmic reticulum with a modal density of 1.16 g/cm3. The uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase equilibrated at a higher density with a peak at a model density of 1.174 g/cm3. Its marked overlap with the distribution of NADPH-cytochrome c reductase suggests that the major activity of uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase is also associated with smooth endoplasmic reticulum membranes, whereas minor proportions of enzyme activity are present in the rough endoplasmic reticulum. Association of both glucosyltransferases with membranes derived from Golgi-complex or plasma membranes could be excluded by treatment of microsomes with membrane reagents prior to isopycnic centrifugation. Digitonin did not alter the equilibrium densities of the glucosyltransferases and endoplasmic reticulum markers in contrast to markers of plasma membranes and the Golgi-complex shifting to higher densities. The reversed effect was observed in case of pretreatment of microsomes with pyrophosphate known to detach ribosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

The subcellular localization of a bile acid glucosyltransferase in rat liver.

Formation of bile acid glucosides occurs in rat liver homogenate with a specific enzyme activity of 0.014 +/- 0.001 nmol per min per mg protein. Subcellular fractionation of rat liver by differential centrifugation revealed an enrichment of bile acid glucosyltransferase activity both in the mitochondrial-lysosomal fraction and in microsomes with a recovery of 38.8 +/- 4.6% and 37.7 +/- 1.7%, respectively, of enzyme activity in the homogenate. Subfractionation of the mitochondrial-lysosomal fraction after treatment of rats with Triton WR 1339 showed an almost exclusive association of bile acid glucosyltransferase activity with purified lysosomes ("tritosomes"). After subfractionation of microsomes by analytical gradients, bile acid glucosyltransferase was bimodally distributed with peaks at modal densities of 1.09 g/cm3 and 1.16 g/cm3, respectively. If microsomes were pretreated with pyrophosphate, a membrane perturbant known to strip ribosomes, only the peak of bile acid glucosyltransferase at higher density (1.16 g/cm3) and UDP-glucuronosyltransferase (marker of endoplasmic reticulum) shifted to a similar lower equilibrium density. Both enzymes were unaffected in their distribution by pretreatment of microsomes with digitonin. In contrast, markers of plasma membranes (5'-nucleotidase) and the Golgi-complex (galactosyltransferase) shifted to higher equilibrium densities after digitonin treatment, but were unaltered in their distribution after pyrophosphate. Bile acid glucosyltransferase activity in the lower density range with a peak at 1.09 g/cm3 did not show any association with the density distributions of known marker enzymes. In purified microsomal fractions obtained by preparative gradients, bile acid glucosyltransferase activity was enriched in enzyme activity by 1.4-fold in rough and by 2.3-fold in smooth endoplasmic reticulum, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Diagnostic value of indirect pancreatic function test in serum of anuric patients with chronic renal failure.

Although patients with chronic renal failure have a high incidence of chronic pancreatic disease, the condition is frequently overlooked. We have modified the pancreolauryl test--an indirect pancreatic function test--for anuric patients. The test permitted good discrimination between patients with chronic pancreatic disease and those with a normal pancreas when serum levels of fluorescein were measured 10 h after administration with a standard meal. The sensitivity at this time interval was 80% and the specificity 83%. We conclude that the pancreolauryl test with serum measurements provides a simple, noninvasive, and reliable diagnostic test for chronic pancreatic disease in anuric patients with chronic renal failure.

Anuria↗
PubMed1994

Positions of conjugation of bile acids with glucose and N-acetylglucosamine in vitro.

In order to establish the position of conjugation of bile acids with glucose or N-acetylglucosamine, glucosides of chenodeoxycholic and hyodeoxycholic acids and of 13C-labeled cholic, lithocholic, chenodeoxycholic, hyodeoxycholic, and ursodeoxycholic acids, and N-acetylglucosaminides of ursodeoxycholic, isoursodeoxycholic, 3-dehydro-ursodeoxycholic, and ursodeoxycholylglycine were synthesized in vitro. The conjugates were purified by anion-exchange chromatography and reversed-phase HLPC and were analyzed by gas chromatography-mass spectrometry. The glucosides of chenodeoxycholic and hyodeoxycholic acids were also analyzed after periodate and chronic acid oxidation. All conjugates were analyzed by fast atom bombardment mass spectrometry with collision-induced dissociation. Glucose conjugation was shown to occur at C-3 in all bile acid glucosides studied. In contrast, the selective N-acetylglucosaminidation of 7 beta-hydroxy bile acids was shown to occur at the 7 beta-position.

Acetylglucosamine↗
PubMed1994

Midazolam and ketamine as premedication in colonoscopies: a pharmacodynamic study.

As colonoscopy is often painful, a premedication appears to be indispensable. Commonly, benzodiazepines, i.e. midazolam, alone or in combination with analgesic drugs are used. Besides all advantages, midazolam especially is known to have the risk of oversedation and respiratory depression. Therefore it should be used at minimal dose. In a double-blind, randomized study, three premedication-schedules of midazolam (mid) plus ketamine (ket) were compared in 33 patients, aged between 8 and 60 years, with regard to safety and acceptance by patients and endoscopist. I: ket 1 mg/kg+mid 0.1 mg/kg, max. 5 mg II: ket 1 mg/kg+mid 0.05 mg/kg, max. 2.5 mg III: ket 0.75 mg/kg+mid 0.1 mg/kg, max. 5 mg Oxygen-saturation, heart rate and blood pressure were recorded as well as the evaluations of sedation, cooperation and complaint of pain. To assess the recovery-time of the patients, the reaction time and the attention were evaluated by "Wiener's determination apparatus" and "test d2", respectively, before and at 1, 2, 3 and 4 hours after premedication. Medication I resulted in heavy sedation, good cooperation and amnesia but had the strongest tendency towards hypoxemia. Under schedule III, reduced cooperation and acceptance were seen due to a strong experience of pain. The best conditions during the examination with regard to cooperation, experience of pain and acceptance were found after premedication II without relevant depression of vital parameters. It can be concluded that midazolam can be used at minimal recommended doses as premedication for colonoscopy if combined with ketamine in a sufficient analgesic dosage.

Adolescent↗
PubMed1993

[Internal bile duct drainage using self-expanding metal stents in benign and malignant bile duct obstruction].

Within a 4-year period, 24 patients were treated by internal biliary drainage using self-expanding wall stents. In 3 patients, a benign and in 21 patients a malignant obstruction were present. The stents were successfully placed in all cases with an incomplete tumour coverage in three cases. Complete relief of icteric symptoms was seen in 18 out of 24 cases. Acute complications requiring additional treatment occurred in 5 patients. Average survival time was 93 days for malignant disease and 26 months for benign lesions. Cumulative patency after 200 days was 63% for stents placed in malignant obstructions. Stents in benign obstructions remained open in all cases.

Aged↗
PubMed1993

Mn-DPDP in MR imaging of pancreatic adenocarcinoma: initial clinical experience.

Manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (DPDP) was tested as a contrast agent for magnetic resonance imaging of pancreatic adenocarcinoma in 15 patients. At enhanced T1-weighted spin-echo (SE) and enhanced T1-weighted gradient-echo (GRE) imaging, statistically significant increases in signal-to-noise ratio (S/N) for the pancreas (21% and 92%, respectively) and contrast-to-noise ratio (C/N) (91% and 209%, respectively) were found. The C/N at enhanced T1-weighted SE imaging was superior to that at unenhanced imaging, including T2-weighted SE imaging (P = .001). Subjective image analysis showed that delineation of the pancreas and pancreatic tumors was clearly improved (P = .05) on enhanced T1-weighted SE and GRE images compared with on unenhanced T1- and T2-weighted images. The liver enhanced 19% at T1-weighted SE imaging and 90% at T1-weighted GRE imaging. There was a significantly higher S/N increase in hepatic parenchyma than in pancreatic tissue at enhanced T1-weighted GRE imaging (P = .0026) but not at enhanced T1-weighted SE imaging.

Adenocarcinoma↗
PubMed1993

[Fibronectin--a key substance in pathogenesis of liver cirrhosis?].

Diffuse and chronic liver damage leads to scar formation of the liver structure accompanied with a disproportionate increase of the extracellular matrix (ECM) constituents. Therapeutic intervention in fibrogenesis with its serious clinical consequences requires analysis of structure and cellular sources of ECM. Fibronectin (FN) is a high molecular weight glycoprotein and increases first among ECM proteins during liver fibrosis. The following report summarizes the crucial aspects of FN during fibrogenesis. Besides its controvertible role as initiator or regulator of fibrogenesis FN plays an important role as a scaffold for other matrix proteins.

Animals↗
PubMed1992

Beta-glucosidase activity towards a bile acid glucoside in human liver.

Human liver contains hydrolytic activity toward 3 beta-glucosido-chenodeoxycholic acid. This beta-glucosidase activity, localized predominantly in the microsomal fraction, was optimally active in the presence of divalent metal ions close to pH 5.0 and was inhibited by EDTA. Kinetic parameters and other catalytic properties of hydrolytic activity towards 3 beta-glucosido-chenodeoxycholic acid from human liver microsomes are described.

Cations, Divalent↗
PubMed1992

Bedside ultrasound in decision making for emergency surgery: its role in medical intensive care patients.

During an 18-month period the authors followed 1,024 patients referred to a general medical intensive care unit. A total of 7% of these patients underwent emergency surgery at some point during their admission. The role of abdominal ultrasound in the decision-making process for these emergency surgical interventions was evaluated and the patients were identified for whom the pathologic result of sonography was regarded sufficient to operate without any additional imaging procedures. Of 71 patients with unexpected surgical emergencies, abdominal ultrasound provided a definite diagnosis for 18 patients (25%), and the decision to operate could be made without delaying for further or more invasive diagnostic techniques. In all cases the sonographic diagnosis was confirmed during the operation. The critical care patients most likely to benefit from bedside ultrasound in a surgical emergency were those with hemorrhage of unknown origin (44%) or septicemia from an undetected focus (39%). The most frequent site of operation where ultrasound was considered diagnostic was the urinary tract (56%), particularly in emergencies following renal transplantation.

Abdomen, Acute↗
PubMed1992

Bile acid N-acetylglucosaminidation. In vivo and in vitro evidence for a selective conjugation reaction of 7 beta-hydroxylated bile acids in humans.

The aim of this study was to define whether N-acetylglucosaminidation is a selective conjugation pathway of structurally related bile acids in humans. The following bile acids released enzymatically from N-acetylglucosaminides were identified: 3 alpha,7 beta-dihydroxy-5 beta-cholanoic (ursodeoxycholic), 3 beta, 7 beta-dihydroxy-5 beta-cholanoic (isoursodeoxycholic), 3 beta,7 beta-dihydroxy-5 alpha-cholanoic (alloisoursodeoxycholic), 3 beta,7 beta-dihydroxy-5-cholenoic, 3 alpha,7 beta,12 alpha-trihydroxy-5 beta-cholanoic, and 3 alpha,6 alpha,7 beta-trihydroxy-5 beta-cholanoic acids. The selectivity of conjugation was studied by administration of 0.5 g ursodeoxycholic (UDCA) or hyodeoxycholic (HDCA) acids, labeled with 13C, to patients with extrahepatic cholestasis, and of 0.5 g of 13C-labeled chenodeoxycholic acid (CDCA) to patients with extra- or intrahepatic cholestasis. After administration of [24-13C]-CDCA, labeled glucosides, and the glucuronide of CDCA were excreted in similar amounts. Labeled N-acetylglucosaminides of UDCA and isoUDCA were also formed. When [24-13C]-UDCA was given, 13C-label was detected in the N-acetylglucosaminide, the glucosides, and the glucuronide of UDCA, and in the N-acetylglucosaminide of isoUDCA. In the patient studied, 32% of the total UDCA excreted in urine was conjugated with N-acetylglucosamine. In contrast, 96% of the excreted amount of [24-13C]HDCA was glucuronidated, and 13C-labeled glucosides but no N-acetylglucosaminide were detected. The selectivity of N-acetylglucosaminidation towards bile acids containing a 7 beta-hydroxyl group was confirmed in vitro using human liver and kidney microsomes and uridine diphosphate glucose (UDP)-N-acetylglucosamine. These studies show that N-acetylglucosaminidation is a selective conjugation pathway for 7 beta-hydroxylated bile acids.

Acetylglucosamine↗
PubMed1991

Synthesis of 13C-labeled chenodeoxycholic, hyodeoxycholic, and ursodeoxycholic acids for the study of bile acid metabolism in liver disease.

In order to study the glycosidic conjugation of chenodeoxycholic, hyodeoxycholic, and ursodeoxycholic acids in patients with cholestasis after oral administration of pharmacological amounts of the respective bile acids avoiding the application of radioactive tracers we synthesized [24-13C]chenodeoxycholic, [24-13C]hyodeoxycholic, and [24-13C]ursodeoxycholic acids. The reaction intermediates of the bile acid syntheses were characterized by infrared spectroscopy. Purity was confirmed using thin-layer chromatography as well as gas chromatography-mass spectrometry. The 13C atom excess of approximately 90% of the synthesized bile acids was the same as the 13C atom excess of the sodium [13C]cyanide used for the labeling reaction confirming the successful synthesis. After oral administration of 0.5 g of [24-13C]ursodeoxycholic acid to a healthy volunteer, 13C label was detected in the nonamidated and glycine- or taurine conjugated glucosides and the N-acetylglucosaminide of ursodeoxycholic acid in urine. This establishes ursodeoxycholic acid as the first bile acid so far known to undergo both of the recently described glycosidic conjugation reactions in humans.

Administration, Oral↗
PubMed1991

Isolation and characterization of hyodeoxycholic-acid: UDP-glucuronosyltransferase from human liver.

The enzyme hyodeoxycholic-acid: UDP-glucuronosyltransferase was purified about 230-fold from a solubilized human liver microsomal preparation utilizing anion-exchange chromatography, ampholyte-displacement chromatography and UDP-hexanolamine--Sepharose affinity chromatography. The homogeneity of the final enzyme preparation was judged by two criteria: the appearance of a single band of Mr 52000 in SDS/PAGE; the elution of a single peak in reversed-phase FPLC. The isolated enzyme catalyzed the glucuronidation of the 6 alpha-hydroxy bile acids hyodeoxycholic and hyocholic acids, and of the steroid hormone estriol, with a ratio of relative reaction rates of 13:1:2.7. UDP-glucuronosyltransferase activities toward the 3 alpha-hydroxy bile acid lithocholic acid, androsterone, testosterone, bilirubin and p-nitrophenol were not detectable in the pure enzyme preparation and were shown to be separated from enzyme activity toward hyodeoxycholic acid during ampholyte-displacement chromatography and/or UDP-hexanolamine--Sepharose affinity chromatography. Two-substrate kinetic analysis of hyodeoxycholic-acid-conjugating activity gave a sequential mechanism with apparent Km values of 12 microM and 4 microM for hyodeoxycholic acid and UDP-glucuronic acid, respectively. Phospholipids were required for reconstitution of maximal activity toward hyodeoxycholic acid. Phosphatidylcholine was the most effective activator of enzyme activity.

Bile Acids and Salts↗