scholarly journals Multiplicity of Hepatic Excretory Mechanisms for Organic Anions

1969 ◽  
Vol 53 (2) ◽  
pp. 238-247 ◽  
Author(s):  
Seymour Alpert ◽  
Michael Mosher ◽  
Alan Shanske ◽  
Irwin M. Arias
Keyword(s):  
Biliary Excretion ◽  
Organic Anion ◽  
Organic Anions ◽  
Bile Pigment ◽  
Johnson Syndrome ◽  
One Step

Previous studies based upon competition between different organic anions for biliary excretion in vivo have suggested that all organic anions share a common hepatic secretory mechanism. Corriedale sheep with an inherited defect in organic anion excretion by the liver were used to study this problem directly without the need for competition studies, the results of which are difficult to analyze. Maximal biliary excretion of sulfobromphthalein (BSP) in mutant Corriedale sheep was less than 7% of that observed in normal sheep whereas maximal biliary excretion of taurocholate, the major organic anion in sheep bile, was not different in mutant and normal sheep. Taurocholate infusion enhanced maximal hepatic excretion of BSP in normal but not in mutant sheep. These studies of an inheritable disorder which appears to be identical to the Dubin-Johnson syndrome in man, demonstrate that taurocholate excretion requires at least one step in biliary excretion which is not required by other organic anions such as bile pigment, porphyrins, drugs, and dyes.

Novel aspects of the transport of organic anions by the malpighian tubules of Drosophila melanogaster

2000 ◽  
Vol 203 (23) ◽  
pp. 3575-3584 ◽  
Author(s):  
S.M. Linton ◽  
M.J. O'Donnell
Keyword(s):  
Drosophila Melanogaster ◽  
Organic Acid ◽  
Organic Anion ◽  
Indigo Carmine ◽  
Organic Anions ◽  
Malpighian Tubules ◽  
Principal Cells ◽  
Anion Transporters ◽  
Mode Of Transport

Para-aminohippuric acid (PAH) is a negatively charged organic ion that can pass across the epithelium of Malpighian tubules. Its mode of transport was studied in Malpighian tubules of Drosophila melanogaster. PAH transport was an active process, with a K(m) of 2. 74 mmol l(−)(1) and a V(max) of 88.8 pmol min(−)(1). Tubules had a low passive permeability to PAH, but PAH transport rates (832 nmol min(−)(1)mm(2)) and concentrative ability ([PAH](secreted fluid):[PAH](bath)=81.2) were the highest measured to date for insects. Competition experiments indicated that there were two organic anion transporters, one that transports carboxylate compounds, such as PAH and fluorescein, and another that transports sulphonates, such as amaranth and Indigo Carmine. PAH transport appears to be maximal in vivo because the rate of transport by isolated tubules is not increased when these are challenged with cyclic AMP, cyclic GMP, leucokinin I or staurosporine. Basolateral PAH transport was inhibited by ouabain and dependent on the Na(+) gradient. The Malpighian tubules appeared not to possess an organic acid/ α -keto acid exchanger because PAH accumulation was not affected by low concentrations (100 μmol l(−)(1)) of α -keto acids (α -ketoglutarate, glutarate, citrate and succinate) or the activity of phosphokinase C. PAH transport may be directly coupled to the Na(+) gradient, perhaps via Na(+)/organic acid cotransport. Fluorescence microscopy showed that transport of the carboxylate fluorescein was confined to the principal cells of the main (secretory) segment and all the cells of the lower (reabsorptive) segment. Organic anions were transported across the cytoplasm of the principal cells both by diffusion and in vesicles. The accumulation of punctate fluorescence in the lumen is consistent with exocytosis of the cytoplasmic vesicles. Apical PAH transport was independent of the apical membrane potential and may not occur by an electrodiffusive mechanism.

Biliary secretion in elasmobranchs. II. Hepatic uptake and biliary excretion of organic anions

1976 ◽  
Vol 230 (4) ◽  
pp. 974-981 ◽  
Author(s):  
JL Boyer ◽  
J Schwarz ◽  
N Smith
Keyword(s):  
Biliary Excretion ◽  
Binding Proteins ◽  
Organic Anion ◽  
Sodium Taurocholate ◽  
Hepatic Clearance ◽  
Hepatic Uptake ◽  
Organic Anions ◽  
Transport Systems ◽  
Raja Erinacea ◽  
Low Concentrations

[35S]Bromosulfophthalein ([35C]BSP), [14C]sodium taurocholate ([14C]NaTC), AND 10 MG OF UNLABELED BSP.and of phenol-3,6-dibromophthalein disulfonate (DBSP) per kilogram body weight were injected in the caudal artery of free-swimming dogfish sharks (Squalus acanthias) and small skates (Raja erinacea). Twenty-four hours later, 85.8 +/- 15.7% of [35S]BSP was recovered in bile and liver in dogfish and 78.4 +/- 9.9% in skates. Similar results were obtained for [14C]NaTC. Unlabeled BSP or DBSP (10 mg/kg body wt) were also selectively excreted in bile over a 4-day period and at comparable rates in both species. More than 85% of [35S]BSP, BSP, and DBSP in bile was in unconjugated form. Selective hepatic clearance of BSP occurred despite nonselective binding to liver homogenates and very low concentrations of binding proteins in liver cytosol. Analysis of the organic anion plasma disappearance curves suggest that the clearance of anions into bile in elasmobranchs is delayed disproportionately relative to hepatic uptake. Albumin-BSP infusions did not prevent selective hepatic uptake of [35S]BSP, although biliary excretion was delayed further. These studies demonstrate that transport systems for biliary excretion of organic anions evolved prior to migration of marine life from the sea and relatively independently of intrahepatic conjugation and organic anion-binding proteins.

Reduced folate derivatives are endogenous substrates for cMOAT in rats

1998 ◽  
Vol 275 (4) ◽  
pp. G789-G796 ◽  
Author(s):  
Hiroyuki Kusuhara ◽  
Yong-Hae Han ◽  
Minoru Shimoda ◽  
Eiichi Kokue ◽  
Hiroshi Suzuki ◽  
...  
Keyword(s):  
Biliary Excretion ◽  
Organic Anion ◽  
Membrane Vesicles ◽  
Organic Anion Transporter ◽  
Sprague Dawley ◽  
Anion Transporter ◽  
Bile Drainage ◽  
Endogenous Substrates

We examined the role of the canalicular multispecific organic anion transporter (cMOAT) in the biliary excretion of reduced folate derivatives in vivo and in vitro using normal [Sprague-Dawley rats (SDR)] and mutant [Eisai hyperbilirubinemic rats (EHBR)] rats whose cMOAT is hereditarily deficient. In vivo, the biliary excretion of endogenous tetrahydrofolate (H4PteGlu), 5-methyltetrahydrofolate (5-CH3-H4PteGlu), and 5,10-methylenetetrahydrofolate (5,10-CH2-H4PteGlu) in EHBR was reduced to 8.2%, 1.9%, and 5.5% of those in SDR, respectively, whereas that of 10-formyltetrahydrofolate (10-HCO-H4PteGlu) was detected only in SDR and not in EHBR. Bile drainage caused reduction of endogenous plasma folate concentrations in SDR but not in EHBR. In vitro, significant ATP-dependent uptake of3H-labeled 5-CH3-H4PteGlu into canalicular membrane vesicles was observed only in SDR. This ATP-dependent uptake was saturable with a Michaelis constant ( K m) value of 126 μM, which was comparable with its inhibitor constant ( K i) value of 121 μM for the ATP-dependent uptake of a typical cMOAT substrate, 2,4-dinitrophenyl- S-glutathione (DNP-SG). Vice versa, DNP-SG inhibited the uptake of 5-CH3-H4PteGlu with a K i of 35 μM, which was similar to its K m value. In addition, H4PteGlu and 5,10-CH2-H4PteGlu also inhibited the ATP-dependent uptake of DNP-SG. These results indicate that 5-CH3-H4PteGlu and other derivatives are transported via cMOAT. Therefore, reduced folate derivatives are the first endogenous substrates for cMOAT that do not contain glutathione, glucuronide, or sulfate moieties.

scholarly journals Interactions between organic anions, micelles and vesicles in model bile systems

1996 ◽  
Vol 320 (3) ◽  
pp. 917-923 ◽  
Author(s):  
Henkjan J. VERKADE ◽  
Marjan A. C. de BRUIJN ◽  
Menno A. BRINK ◽  
Herre TALSMA ◽  
Roel J. VONK ◽  
...  
Keyword(s):  
Bile Salt ◽  
Mixed Micelles ◽  
Membrane Lipids ◽  
Organic Anion ◽  
Organic Anions ◽  
In Vitro Models ◽  
Biliary Lipid ◽  
Lipid Secretion

Biliary lipid secretion probably involves both ‘micellization’ and ‘vesiculization’ of bile-canalicular membrane lipids. Several hydrophilic organic anions inhibit the secretion of lipids into the bile without altering bile salt secretion [Verkade, Vonk and Kuipers (1995) Hepatology 21, 1174–1189]. Hydrophobic organic anions do not interfere with biliary lipid secretion. We investigated whether the organic-anion-induced inhibition of biliary lipid secretion in vivo could be attributed to inhibition of micellization, by the application of in vitro models of micellization. Carboxyfluorescein was entrapped in a self-quenching concentration in small unilamellar vesicles (SUV) composed of cholesterol/egg phosphatidylcholine (molar ratios 0, 0.2 and 0.5). Certain organic anions clearly affected the bile-salt-induced release of fluorescence from these SUV, reflecting interference with micellization. However, the effects of hydrophilic and hydrophobic organic anions did not correspond with their effects on biliary lipid secretion in vivo, irrespective of the bile salt species used (taurocholate, taurodeoxycholate or tauroursodeoxycholate) and of the lipid composition of the SUV. Ultracentrifugation and dynamic light-scattering studies indicated that organic anions do interact with bile salt/phosphatidylcholine/cholesterol mixed micelles, but that they do not inhibit micellization, for example by competing with phosphatidylcholine and/or cholesterol for incorporation into mixed micelles. In conclusion, the present in vitro data indicate that the in vivo mechanism of organic-anion-induced inhibition of biliary lipid secretion is not mediated by inhibition of micellization.

Hepatobiliary Kinetics of 113mIn-Phenolphthalexon

1981 ◽  
Vol 20 (02) ◽  
pp. 90-93
Author(s):  
P.B. Parab ◽  
U.R. Raikar ◽  
R.D. Ganatra ◽  
M. C. Patel
Keyword(s):  
Biliary Excretion ◽  
Iminodiacetic Acid ◽  
Organ Distribution ◽  
Liver Uptake ◽  
On Line ◽  
Rapid Clearance ◽  
Chemical Purity ◽  
Kinetics Of ◽  
High Liver

Phenolphthalexon, a compound with iminodiacetic acid as a functional group, has been labelled with 113mIn to high chemical purity and its usefulness in studies of biliary excretion patency has been studied. Organ distribution of 113mIn-phenolphthalexon in mice was characterized by high liver uptake (50.8% of the administered dose after 5 min) and rapid clearance through the gall bladder. An animal model for studying obstruction of biliary excretion has been developed. Data on the kinetics of the radiopharmaceutical were obtained by collecting in-vivo data through an on-line computer.

scholarly journals In Vivo Identification of Intermediate Stages of the DNA Inversion Reaction Catalyzed by the Salmonella Hin Recombinase

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1649-1663
Author(s):  
Oliver Z Nanassy ◽  
Kelly T Hughes
Keyword(s):  
Amino Acids ◽  
Biochemical Analysis ◽  
Mutational Analysis ◽  
Recombination Reaction ◽  
Recombination Site ◽  
Dna Inversion ◽  
Hin Recombinase ◽  
One Step ◽  
A Site

Abstract The Hin recombinase catalyzes a site-specific recombination reaction that results in the reversible inversion of a 1-kbp segment of the Salmonella chromosome. The DNA inversion reaction catalyzed by the Salmonella Hin recombinase is a dynamic process proceeding through many intermediate stages, requiring multiple DNA sites and the Fis accessory protein. Biochemical analysis of this reaction has identified intermediate steps in the inversion reaction but has not yet revealed the process by which transition from one step to another occurs. Because transition from one reaction step to another proceeds through interactions between specific amino acids, and between amino acids and DNA bases, it is possible to study these transitions through mutational analysis of the proteins involved. We isolated a large number of mutants in the Hin recombinase that failed to carry out the DNA exchange reaction. We generated genetic tools that allowed the assignment of these mutants to specific transition steps in the recombination reaction. This genetic analysis, combined with further biochemical analysis, allowed us to define contributions by specific amino acids to individual steps in the DNA inversion reaction. Evidence is also presented in support of a model that Fis protein enhances the binding of Hin to the hixR recombination site. These studies identified regions within the Hin recombinase involved in specific transition steps of the reaction and provided new insights into the molecular details of the reaction mechanism.

scholarly journals T cell mediated hypersensitivity to previously tolerated iodinated contrast media precipitated by introduction of atezolizumab

2021 ◽  
Vol 9 (5) ◽  
pp. e002521
Author(s):  
Sean Hammond ◽  
Anna Olsson-Brown ◽  
Joshua Gardner ◽  
Paul Thomson ◽  
Serat-E Ali ◽  
...  
Keyword(s):  
Contrast Media ◽  
Adverse Reactions ◽  
Stevens Johnson Syndrome ◽  
Iodinated Contrast ◽  
Immune Mediated ◽  
Johnson Syndrome ◽  
Healthy Donors ◽  
Concomitant Medications

Many adverse reactions associated with immune checkpoint inhibitor (ICI) treatments are immunologically driven and may necessitate discontinuation of the ICI. Herein, we present a patient who had been administered the radio contrast media amidotrizoate multiple times without issue but who then developed a Stevens-Johnson syndrome reaction after coadministration of atezolizumab. Causality was confirmed by a positive re-challenge with amidotrizoate and laboratory investigations that implicated T cells. Importantly, the introduction of atezolizumab appears to have altered the immunologic response to amidotrizoate in terms of the tolerance–elicitation continuum. Proof of concept studies demonstrated enhancement of recall responses to a surrogate antigen panel following in-vitro (healthy donors) and in-vivo (ICI patients) administrations of ICIs. Our findings highlight the importance of considering all concomitant medications in patients on ICIs who develop immune-mediated adverse reactions. In the event of some immune-related adverse reactions, it may be critical to identify the culprit antigen-forming entity that the ICIs have altered the perception of rather than simply attribute causality to the ICI itself in order to optimize both patient safety and treatment of malignancies.

scholarly journals Construction of adenovirus vectors simultaneously expressing four multiplex, double-nicking guide RNAs of CRISPR/Cas9 and in vivo genome editing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomoko Nakanishi ◽  
Aya Maekawa ◽  
Mariko Suzuki ◽  
Hirotaka Tabata ◽  
Kumiko Sato ◽  
...  
Keyword(s):  
Target Gene ◽  
Animal Experiments ◽  
Adenovirus Vector ◽  
Mouse Embryonic Fibroblast ◽  
Newborn Mouse ◽  
Guide Rnas ◽  
One Step ◽  
Target Effect

AbstractSimultaneous expression of multiplex guide RNAs (gRNAs) is valuable for knockout of multiple genes and also for effective disruption of a gene by introducing multiple deletions. We developed a method of Tetraplex-guide Tandem for construction of cosmids containing four and eight multiplex gRNA-expressing units in one step utilizing lambda in vitro packaging. Using this method, we produced an adenovirus vector (AdV) containing four multiplex-gRNA units for two double-nicking sets. Unexpectedly, the AdV could stably be amplified to the scale sufficient for animal experiments with no detectable lack of the multiplex units. When the AdV containing gRNAs targeting the H2-Aa gene and an AdV expressing Cas9 nickase were mixed and doubly infected to mouse embryonic fibroblast cells, deletions were observed in more than 80% of the target gene even using double-nicking strategy. Indels were also detected in about 20% of the target gene at two sites in newborn mouse liver cells by intravenous injection. Interestingly, when one double-nicking site was disrupted, the other was simultaneously disrupted, implying that two genes in the same cell may simultaneously be disrupted in the AdV system. The AdVs expressing four multiplex gRNAs could offer simultaneous knockout of four genes or two genes by double-nicking cleavages with low off-target effect.

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