scholarly journals Comparison of prohormone-processing activities in islet microsomes and secretory granules: evidence for distinct converting enzymes for separate islet prosomatostatins.

1984 ◽  
Vol 99 (2) ◽  
pp. 578-587 ◽  
Author(s):  
B D Noe ◽  
G Debo ◽  
J Spiess
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Golgi Complex ◽  
Secretory Granules ◽  
Gradient Centrifugation ◽  
Differential Distribution ◽  
Ph Optimum ◽  
Prohormone Processing

In previous work we have examined the nature of converting enzymes for proinsulin, proglucagon, and prosomatostatin-I (PSS-I) in secretory granules isolated from anglerfish islets. The purpose of the present study was to extend the examination of precursor conversion to islet microsomes and to compare prohormone processing, including that of PSS-I and prosomatostatin-II (PSS-II), in islet secretory granules and microsomes. Microsomes (rough endoplasmic reticulum [RER] and Golgi complex) and secretory granules were prepared from anglerfish islets by differential and discontinuous density-gradient centrifugation. Microsomes were further fractionated into Golgi- and RER-enriched subfractions. Lysed secretory granule or microsome preparations were incubated in the presence of a mixture of radioactively labeled islet prohormones. Extracts of products generated were subjected to analysis by gel filtration and high-pressure liquid chromatography. Accuracy of product cleavage was monitored by comparing high-pressure liquid chromatography retention times from the radiolabeled in vitro conversion products with the retention times of labeled products from tissue extracts. All converting activity in microsomes was found to be similar to that in granules in that it had a pH optimum near pH 5 and was inhibited by p-chloromercuribenzoate. No significant differences in the converting activity of Golgi complex- and RER-enriched subfractions of microsomes was observed. The proinsulin, proglucagon, and PSS-II converting-enzymes, which were found in islet secretory granules, were also present and membrane-associated in islet microsomes. However, converting activity for PSS-I was displayed only in secretory granules. This suggests that two or more separate enzymes are involved in processing PSS-I and PSS-II, and that these enzymes have either differential distribution or differential activity in RER/Golgi complex and secretory granules. The demonstration of converting enzyme activity in islet microsomes supports the proposal that these enzymes may be synthesized at the RER and are internalized along with the prohormones.

Vasopressin is metabolized by a trypsinlike enzyme in guinea pig amniotic fluid

1989 ◽  
Vol 257 (3) ◽  
pp. E354-E360 ◽  
Author(s):  
C. F. Uyehara ◽  
A. K. Sato ◽  
J. R. Claybaugh
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Guinea Pig ◽  
Amniotic Fluid ◽  
High Pressure Liquid Chromatography ◽  
Trypsin Inhibitor ◽  
Arginine Vasopressin ◽  
Proteolytic Enzyme

We have demonstrated that arginine vasopressin (AVP) is degraded to desglycinamide AVP by a trypsinlike enzyme found in guinea pig amniotic fluid. Incubation of [3H]AVP with guinea pig amniotic fluid in vivo or in vitro produced a metabolite that comigrated on high-pressure liquid chromatography with desglycinamide AVP in three different buffer systems. Also, AVP antisera that cross-reacted with standard desglycinamide AVP could detect this amniotic fluid metabolite. Because the enzyme responsible for the cleavage of glycinamide from AVP was likely to be trypsin, experiments with aprotinin, a trypsin inhibitor, were conducted. Results demonstrated that the production of the amniotic fluid AVP metabolite could be completely blocked in the presence of the trypsin inhibitor. In addition, examination of amniotic fluid collected from fetuses in the second half of gestation (term = 68 days) showed that AVP could not be metabolized to desglycinamide AVP until after 52 days of gestation. In conclusion, AVP appears to be metabolized by a trypsinlike enzyme in amniotic fluid, and because trypsin is a general proteolytic enzyme, the amniotic compartment may also serve as a clearance site for other proteins.

Mechanism of Development of Bronze Baby Syndrome in Neonates Treated with Phototherapy

PEDIATRICS ◽  
1982 ◽  
Vol 69 (3) ◽  
pp. 273-276
Author(s):  
Shoju Onishi ◽  
Susumu Itoh ◽  
Kenichi Isobe ◽  
Hajime Togari ◽  
Hideyuki Kitoh ◽  
...  
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Radical Reaction ◽  
The Body ◽  
Brown Pigment ◽  
Free Radical Reaction ◽  
Serum Concentrations ◽  
Excretory Function

Comparisons of serum concentrations of unknown pigment and photobiirubin IXα, the two main bilirubin photoproducts, were made during phototherapy in infants with and without bronze baby syndrome who were treated similarly. The serum concentrations of unknown pigment estimated by high-pressure liquid chromatography in infants with the bronze baby syndrome were significantly increased in comparison with those in the control hyperbilirubinemic neonates during phototherapy. However, there was no difference in the serum concentrations of photobilirubin IXα between infants with bronze baby syndrome and the control groups. The unknown pigment separated from bilirubin photoproducts obtained from experiments in vitro by high-pressure liquid chromatography was gradually decomposed into brown products that showed the absorption spectrum similar to that of the serum of infants with bronze baby syndrome. This fact is probably due to reduction in hepatic excretory function of bilirubin photoproducts, especially unknown pigment, because its main excretory pathway is the biliary route. The pigment accumulated in the body may be polymerized and forms bilifuscin-like substances following a free radical reaction. It is concluded that the brown pigment is formed via unknown pigment.

scholarly journals Pitfalls in Cefepime Titration from Human Plasma: Plasma- and Temperature-Related Drug Degradation In Vitro

2002 ◽  
Vol 46 (11) ◽  
pp. 3654-3656 ◽  
Author(s):  
Denis Bugnon ◽  
Eric Giannoni ◽  
Paul Majcherczyk ◽  
Michel P. Glauser ◽  
Philippe Moreillon
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Human Plasma ◽  
High Pressure Liquid Chromatography ◽  
Drug Degradation ◽  
Related Drug

ABSTRACT While developing a high-pressure liquid chromatography assay for cefepime in plasma, we observed significant drug degradation at 20 and 37°C but not at 4°C. This plasma-related degradation persisted after protein removal. This warrants caution regarding cefepime assays for pharmacokinetic and pharmacodynamic studies of cefepime in vitro and in vivo.

scholarly journals High-pressure liquid chromatographic analysis of anaerobic photoproducts of bilirubin-IX α in vitro and its comparison with photoproducts in vivo

1980 ◽  
Vol 190 (3) ◽  
pp. 527-532 ◽  
Author(s):  
S Onishi ◽  
N Kawade ◽  
S Itoh ◽  
K Isobe ◽  
S Sugiyama
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Biological Fluids ◽  
Gel Filtration ◽  
Filtration Method ◽  
Bilirubin Metabolism ◽  
Liquid Chromatographic

To carry out photochemical experiments under conditions similar to those prevailing for neonatal bilirubin metabolism in jaundice phototherapy, we have studied photoproducts produced by the action of light on a bilirubin—albumin solution and further clarified the relationship between the photoproducts obtained from experiments in vitro and in vivo. (1) An accurate and sensitive separation method by high-pressure liquid chromatography for photoproducts of bilirubin under anaerobic irradiation of visible light is described. (2) There were two main photoproducts obtained from experiments both in vivo and in vitro. (3) Exact correspondence of retention time on high-pressure liquid chromatography, diazo-reactivity, thermal reversion and absorption-spectrum maxima was observed between unknown pigment and photobilirubin-IX alpha from biological fluids, and the comparable peaks 2 and 3 from experiments in vitro. (4) The behaviour of photoproducts in various solutions in the absence of light and O2 is described. (5) A lower affinity of photoproducts, especially unknown pigment, for human serum albumin than with bilirubin-IX alpha for the albumin was demonstrated by the gel-filtration method.

The Effects on Neonatal Hyperbilirubinaemia of Parenteral Administration of Valium to Women in Labour

1978 ◽  
Vol 6 (6) ◽  
pp. 468-470 ◽  
Author(s):  
R Stockmann ◽  
D Sidiropoulos ◽  
G Wendt
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Cord Blood ◽  
High Pressure Liquid Chromatography ◽  
Sodium Benzoate ◽  
Newborn Infants ◽  
Parenteral Administration ◽  
Intramuscular Administration ◽  
Therapeutic Doses

Following intramuscular administration of Valium® Roche to the mother during labour, the concentration of sodium benzoate (included in the solvent of Valium) was measured in the cord-blood of 8 newborn infants. After administration of therapeutic doses of Valium to the mother, it was found that sodium benzoate—which displaces bilirubin from albumin in vitro— was present in the cord blood in concentrations insufficient to cause clinically important displacement of bilirubin from albumin. Benzoate analyses were carried out using high-pressure liquid chromatography.

scholarly journals Phase II Metabolism of Asarone Isomers In Vitro and in Humans Using HPLC-MS/MS and HPLC-qToF/MS

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2032
Author(s):  
Lena Hermes ◽  
Janis Römermann ◽  
Benedikt Cramer ◽  
Melanie Esselen
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Phase Ii ◽  
High Pressure Liquid Chromatography ◽  
Excretion Rate ◽  
Liver Microsomes ◽  
Oral Intake ◽  
Phase Ii Metabolites

(1) Background: Metabolism data of asarone isomers, in particular phase II, in vitro and in humans is limited so far. For the first time, phase II metabolites of asarone isomers were characterized and human kinetic as well as excretion data after oral intake of asarone-containing tea infusion was determined. (2) Methods: A high pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-qTOF-MS) approach was used to identify phase II metabolites using liver microsomes of different species and in human urine samples. For quantitation of the respective glucuronides, a beta-glucuronidase treatment was performed prior to analysis via high pressure liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). (3) Results: Ingested beta-asarone and erythro and threo-asarone diols were excreted as diols and respective diol glucuronide conjugates within 24 h. An excretion rate about 42% was estimated. O-Demethylation of beta-asarone was also indicated as a human metabolic pathway because a corresponding glucuronic acid conjugate was suggested. (4) Conclusions: Already reported O-demethylation and epoxide-derived diols formation in phase I metabolism of beta-asarone in vitro was verified in humans and glucuronidation was characterized as main conjugation reaction. The excretion rate of 42% as erythro and threo-asarone diols and respective asarone diol glucuronides suggests that epoxide formation is a key step in beta-asarone metabolism, but further, as yet unknown metabolites should also be taken into consideration.

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