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P G Killenberg

Publications and source records attributed to P G Killenberg.

31 records · Page 2Linked to original sources
PubMed1980

Identification of the 3-sulfate isomer as the major product of enzymatic sulfation of chenodeoxycholate conjugates.

Thin layer and high performance liquid chromatography identified the 3-monosulfate ester as the predominant product of in vitro enzymatic sulfation of glyco- and taurochenodeoxycholate by rat liver and kidney and hamster liver. The rate of synthesis of the 7-sulfate ester was less than 20% that of the 3-sulfate isomer; in vitro synthesis of the 3,7-disulfate was not definitely seen. Reaction of the enzymatic products with 7 alpha-hydroxysteroid dehydrogenase indicated a molar ratio of 7 alpha-hydroxyl function and SO4 which further supported the identification of the 3-sulfate isomer as the major product.

Animals↗
PubMed1980

Surgical resection for benign and malignant liver disease.

The indications for major hepatic resections in 32 patients and the results are presented. Twelve right lobectomies, eight partial left lobectomies, five left lobectomies, four extended right lobectomies and three partial right lobectomies were performed with a 46% complication rate and an operative mortality rate of 12.5%. Ten primary liver cancers, 12 metastatic lesions, four hemangiomas and six "benign" lesions were removed. Of seven patients with hepatomas, four are alive at an average of 24 months postresection and three have no evidence of recurrence. Of 11 adult patients with metastatic lesions, six are alive at an average of 27 months postresection and three patients have no evidence of recurrence. All four patients with hemangioma are alive at an average of seven years. As in other series, our experience has increased with seven resections prior to 1970 and 25 since. Operative mortality has decreased in that period of time (42% to 4%); however, our complication rate in survivors has remained elevated (25% to 50%). Our experience agrees with others that cautious selection of patients for resection of malignant tumors of the liver can extend survival.

Adolescent↗
PubMed1980

Development of enzymatic conjugation and sulfation of bile acids in hamster liver.

In vitro levels of enzyme activity were measured in liver from fetal and developing hamsters to study the fetal immaturity and postnatal development of bile acid conjugation and sulfation. Sulfation and conjugation were measured in the same animals. Partial reactions of bile acid conjugation were assayed independently; sulfation of conjugated and unconjugated lithocholate was measured separately. From 3 days before to 3 days after birth, specific activity for sulfation of lithocholate and lithocholate conjugates was similar; lithocholate sulfation was 80% of adult levels. In older hamsters, specific activity for sulfation of lithocholate conjugates was significantly higher than that for lithocholate. Specific activities of both partial reactions of bile acid conjugation were 12% of adult levels from 3 days before to 3 days after birth. Thereafter both activities increased together; the ratio of glycine to taurine-dependent conjugation was similar at all ages. The data suggest early development of a separate mechanism for lithocholate sulfation. Enzymes catalyzing bile acid conjugation and sulfation of bile acid conjugates exhibit maximal development after birth.

Animals↗
PubMed1980

Effects of ethinylestradiol on enzymes catalyzing bile acid conjugation and sulfation.

Administration of large doses of estrogens has been shown to result in decreased conjugation and increased sulfation of bile acids as well as cholestasis. There have been no previous studies on the effects of low doses of estrogens on these parameters of bile acid metabolism. Therefore, rats were given ethinylestradiol, 0.06 to 600 micrograms/kg/day subcutaneously for up to 21 days and the in vitro activity of the hepatic conjugation and sulfation enzymes was measured. Conjugating enzyme activity was unchanged at doses below 600 micrograms/kg/day. In contrast, hepatic sulfation of conjugated bile acids increased significantly after 21 days treatment with 0.6 micrograms/kg/day. The magnitude of the increase was both time- and dose-dependent. Increased sulfotransferase activity was noted only in the liver and was specific for conjugated bile acids; there was no change in the rate of sulfation of the unconjugated bile acids or in renal sulfotransferase activity. Increased hepatic bile acid sulfotransferase activity occurred in the presence of normal bile flow and bile acid secretion. These data indicate that treatment with doses of ethinylestradiol comparable to those present in oral contraceptives may lead to readily detectable time- and dose-dependent changes in bile acid sulfation without producing cholestasis. The data also suggest that there may be significant differences in the enzymatic sulfation of conjugated and unconjugated bile acids in the liver.

Acyltransferases↗
PubMed1980

The laboratory method as a variable in the interpretation of serum bilirubin fractionation.

Fractionation of the serum bilirubin into direct and indirect-reacting components has been used in the differentiation of patients with hepatobiliary disease from those with unconjugated hyperbilirubinemia. Previous studies have shown that patients with indirect hyperbilirubinemia usually have total serum bilirubin concentrations less than 5 mg/dl. Therefore, clinically useful methods of fractionating bilirubin must yield reliable results in patients with mild hyperbilirubinemia. Experience with 4 patients with mild hyperbilirubinemia indicated that conflicting results could be obtained from two different laboratories. Therefore, a panel of hyperbilirubinemic sera were submitted to four different laboratories. While there was general agreement in sera containing high concentrations of bilirubin, marked variations were observed in the results reported on sera with less than 5 mg/dl total bilirubin. Finally, clinical and other laboratory parameters were reviewed in patients who had had bilirubin fractionation performed by one or the other of two routine laboratories. In one laboratory, bilirubin fractionation correctly distinguished patients with hepatobiliary disease, while the other laboratory was not able to differentiate patients on the basis of this test. These data suggest that despite the general reported agreement in standard methods for bilirubin fractionation there may be marked differences among methods in ability to reliably fractionate sera with total bilirubin concentrations less than 5 mg/dl.

Adult↗
PubMed1978

Purification and characterization of bile acid-CoA:amino acid N-acyltransferase from rat liver.

An in vitro study of bile acid-CoA:amino acid N-acyltransferase activity of rat liver was undertaken in order to determine whether separate amino acid-specific enzymes catalyzed the formation of glycine and taurine conjugates of bile acids as postulated by others. Polyacrylamide gel electrophoresis of 200-fold purified enzyme localized the glycine- and taurine-dependent activities to a single band. Both activities were optimal at pH 7.8 and showed similar loss of activity at pH 6.0, pH 9.0, in the presence of 5,5'-dithiobis(2-nitrobenzoic acid), and at temperatures exceeding 50 degrees. With the purified fraction, Km for glycine was 31 mM and Km for taurine was 0.8 mM. Km for several bile acid-CoA substrates was approximately 20 micron and independent of the amino acid acceptor. Only amino acids with terminal alpha- or beta-amino groups were active as acyl acceptors. Acyl donors were limited to bile acid-CoA derivatives. The data support the conclusion that the rat has a single bile acid-CoA:amino acid N-acyltransferase. The substrate kinetics are consistent with previous observations that taurine conjugates predominate in rat bile at normal hepatocellular concentrations of glycine and taurine.

Acyltransferases↗
PubMed1978

Measurement and subcellular distribution of choloyl-CoA synthetase and bile acid-CoA:amino acid N-acyltransferase activities in rat liver.

An improved method for assaying choloyl-CoA synthetase activity (E.C. 6.2.1.7) and two methods for specific measurement of bile acid-CoA:amino acid N-acyltransferase activity (E.C. 2.3.1) are described. The methods are shown to be reproducible, linear with respect to time and enzyme protein, and result in estimates of enzymic activity that conform to the theoretical stoichiometry of the individual reactions. Utilizing these methods, the subcellular distribution of the rat liver enzymic activity catalyzing the formation of glycine and taurine conjugates of bile acids is shown. Choloyl-CoA synthetase is associated with the microsomal membranes and bile acid-CoA:amino acid N-acyltransferase activity with the postmicrosomal supernatant. No significant amino acid N-acyltransferase activity is present in the lysosome fraction. These studies provide methods that will permit further study of the individual enzymic reactions involved in the intrahepatic conjugation of bile acids with amino acids.

Acetyltransferases↗
PubMed1976

Coenzyme A derivatives of bile acids-chemical synthesis, purification, and utilization in enzymic preparation of taurine conjugates.

Synthesis of the coenzyme A derivatives of bile acids by the mixed anyhydride method results in a product that is contaminated by unreacted CoASH and bile acid. These compounds can be purified by Sephadex LH-20 chromatography. In each case, the purified product is free of starting materials and exhibits an equimolar ratio of bile acid, coenzyme A, and thioester bond. Millimolar extinction coefficients were calculated for these compounds as A259 nm, 15.03 +/- 0.58; A232 nm, 7.60 +/- 0.17; and A232 nm for the thioester bond, 4.12 +/- 0.17. These CoA derivatives were hydrolyzed in strongly alkaline solution, but were stable at physiologic temperature and pH. Utilization of these compounds in the enzymic preparation of taurine conjugates of bile acids indicated 94% activity. These purified CoA derivatives may be useful in studying the enzymic conjugation of bile acids.

Animals↗
PubMedDate not supplied

Rat hepatic bile acid sulfotransferase: identification of the catalytic polypeptide and evidence for polymeric forms in female rats.

A monoclonal antibody, PK1B, directed against rat liver bile acid sulfotransferase was used for the purification and characterization of the enzyme. Incubation of rat liver supernatant with the antibody followed by immunoprecipitation with Staphylococcus aureus cells demonstrated that PK1B reacted with 90% of the enzymatic activity present in the liver supernatant from female rats and 40 to 50% of the activity in male liver preparations. Immunoadsorption chromatography with PK1B bound to Sepharose isolated active enzyme which was purified greater than 75-fold. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of this preparation in the presence of 2-mercaptoethanol demonstrated three polypeptides: Mr 29,500; 32,500, and 34,000. Western blot analysis indicated that PK1B recognized an epitope which was found only on the Mr 29,500 polypeptide. Two-dimensional gel electrophoresis associated the enzymatic activity with this Mr 29,500 band. High-pressure liquid chromatographic analysis of immunopurified enzyme defined three distinct, enzymatically active protein populations: I (Mr 400,000 to 170,000); II (Mr 130,000), and III (Mr 43,000). An Mr 29,500 polypeptide was the sole constituent of Peaks I and III and a major constituent of Peak II. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence and absence of 2-mercaptoethanol indicated that in Peak II, catalytically active Mr 29,500 protein is associated with the other two polypeptides by disulfide bonds. In contrast, Peak I consists of a polymer of Mr 29,500 polypeptide which is independent of disulfide interaction.

Animals↗