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PubMed1995

Activated liver macrophages in human liver diseases.

Immunohistochemical analysis using monoclonal antibodies specific for cells of monocyte/macrophage lineage reveals that resident liver macrophages have a phenotype distinct from that of monocytes or activated liver macrophages. Liver macrophages consist of heterogeneous cell populations in maturation (matured 25F9-positive and immature 25F9-negative) but the ratio of two populations is constant in normal and diseased livers. The expression of CD14 is down-regulated in resident liver macrophages as compared to that in monocytes, while the expression of 25F9 is up-regulated. On the other hand, the expressions of CD14 and Fc gamma RI are up-regulated in activated liver macrophages in viral and autoimmune hepatitis. In vitro culture of monocytes in medium without cytokines induces the phenotype similar to that of resident liver macrophages. Addition of macrophage-colony stimulating factor or interferon-gamma into the culture medium induces the expression of Fc gamma RI, the phenotype of which resembles that of activated liver macrophages. These results suggest that liver macrophages consist of heterogeneous cell populations and that both phenotype and function are affected by the local milieu of cytokines.

Animals↗
PubMed1999

Tissue inhibitors of metalloproteinases: role in liver fibrosis and alcoholic liver disease.

In liver fibrosis, activated hepatic stellate cells (HSC) play a major role in the deposition of excess extracellular matrix, including fibrillar collagens type I and type III. In addition to matrix protein synthesis, HSC regulate matrix degradation in the liver. This is mediated via a combination of synthesis of matrix (pro)metalloproteinases, which activate these zymogens via specific mechanisms and by inhibiting the active matrix-degrading enzymes via expression of tissue inhibitors of metalloproteinases (TIMPs). There are currently four members of the TIMP family described and of these, both TIMP-1 and TIMP-2 are synthesised by HSC. These observations have led to the suggestion that inhibition of matrix degradation mediated by a change in HSC-expression of TIMPs relative to metalloproteinases, such as interstitial collagenase, may contribute to progression of liver fibrosis. This hypothesis is supported by studies of human liver disease in which TIMP-1 expression is upregulated 5-fold in cirrhotic compared with normal liver. TIMP-1 and TIMP-2 expression is also upregulated in animal models of progressive fibrosis, whereas expression of collagenase is unchanged. In a model which is characterized by natural resolution of liver fibrosis, degradation of the deposited fibrillar liver matrix is accompanied by rapid down-regulation of TIMP-1 expression. In alcoholic liver disease, the role of TIMPs has not been studied exhaustively, but the evidence currently available supports a role for inhibition of matrix degradation by TIMPs in this progressive fibrotic liver disease.

Humans↗
PubMed2005

Effect of rosiglitazone on serum liver biochemistries in diabetic patients with normal and elevated baseline liver enzymes.

OBJECTIVES: Thiazolidinediones (TZD) are recommended to be used cautiously in diabetics with mild elevations in liver enzymes and not to be used in those with alanine aminotransferase>2.5 upper limit normal (ULN). However, studies are not adequate that evaluated the risk of TZD hepatotoxicity in diabetics with elevated liver enzymes. We conducted a study to test if diabetics with elevated liver enzymes have increased risk for hepatotoxicity from rosiglitazone (only TZD available on our formulary). METHODS: This study consisted of two cohorts of patients prescribed rosiglitazone since January 2000. Cohort 1: 210 diabetics with elevated baseline liver enzymes (aspartate aminotransferase (AST)>40 IU/L and/or alanine aminotransferase (ALT)>35 IU/L) who received rosiglitazone, and cohort 2:628 diabetics with normal liver enzymes who received rosiglitazone. Elevations in liver biochemistries over a 12-month period after initiating rosiglitazone were characterized into mild to moderate or severe elevations and into "Hy's rule" based on published criteria. RESULTS: Compared to cohort 2, patients in cohort 1 did not have higher incidence of mild to moderate (10% vs 6.6%, p=0.2) or severe elevations (0.9% vs 0.6%, p=0.9) in liver biochemistries. Similarly, the incidence of liver biochemistry abnormalities meeting the Hy's Rule was statistically not different between the two cohorts (0% vs 0.3%, p=0.9). The frequency of discontinuing rosiglitazone therapy during the follow-up was similar between cohorts 1 and 2 (8.6% vs 8.1%, p=1.0). CONCLUSIONS: These results suggest that diabetics with elevated baseline liver enzymes do not have a higher risk of hepatotoxicity from rosiglitazone than those with normal enzymes.

Alanine Transaminase↗
PubMed1994

Spontaneous development of anti-hepatitis B virus envelope (anti-idiotypic) antibodies in animals immunized with human liver endonexin II or with the F(ab')2 fragment of anti-human liver endonexin II immunoglobulin G: evidence for a receptor-ligand-like relationship between small hepatitis B surface antigen and endonexin II.

In a previous study, we have identified endonexin II (E-II) on human liver plasma membranes as a specific, Ca(2+)-dependent, small hepatitis B surface antigen (HBsAg)-binding protein. In this article, we describe the spontaneous development of anti-HBs antibodies in rabbits immunized with native or recombinant human liver E-II and in chickens immunized with the F(ab')2 fragment of rabbit anti-human liver E-II immunoglobulin G. Anti-HBs activity was not observed in rabbits immunized with rat liver E-II. Cross-reactivity of anti-E-II antibodies to HBsAg epitopes was excluded, since anti-HBs and anti-E-II activities can be separated by E-II affinity chromatography. The existence of an anti-idiotypic antibody is further demonstrated by competitive binding of human liver E-II and this antibody (Ab2) to small HBsAg, suggesting that Ab2 mimics a specific E-II epitope that interacts with small HBsAg. In addition, it was demonstrated that anti-HBs antibodies developed in rabbits after immunization with intact human liver E-II or in chickens after immunization with F(ab')2 fragments of rabbit anti-human liver E-II immunoglobulin G recognize the same epitopes on small HBsAg. These findings strongly indicate that human liver E-II is a very specific small HBsAg-binding protein and support the assumption that human liver E-II is the hepatitis B virus receptor protein.

Animals↗
PubMed1983

Erythropoietin in liver tissue extracts and in liver perfusates from hypoxic rats.

An attempt to evaluate the role of the liver in extrarenal erythropoietin production was made by measuring the content of erythropoietin in homogenates and perfusates from hypoxic rat livers. Extracts from livers from nephric or anephric animals rendered both anemic and hypoxic showed no detectable erythropoietin despite the fact that both plasma and kidney extracts contained large amounts of erythropoietin. This lack of measurable erythropoietin in the liver is not caused by degradation of erythropoietin during the extraction procedure because exogenously added rat erythropoietin was recovered to the same extent from livers or kidney homogenates. More likely, however, it is caused by the fact that extrarenal erythropoietin production accounts for only one-fifth of total erythropoietin production and that the liver mass is about six times that of both kidneys. Consequently, the erythropoietin content of 1 g of liver should be about one-thirtieth of that of 1 g of kidney, an amount that is below the limit of detection of the assay. On the other hand, the 2-h in situ perfusates of livers from similarly stimulated animals contained significant amounts of secreted erythropoietin. It is concluded that the liver participates actively in extrarenal erythropoietin production in the adult rat. However, the small amount expected to be present in tissue homogenates cannot be detected with our current bioassay.

Anemia↗
PubMed1994

T4 uptake into the perfused rat liver and liver T4 uptake in humans are inhibited by fructose.

Recently, we described a two-pool model for 3,5,3'-triiodothyronine uptake and metabolism in the isolated perfused rat liver. Here, we applied this model to investigate transmembrane thyroxine (T4) transport and its possible ATP dependence in vivo. These studies are performed in perfused rat livers during perfusion with or without fructose in the medium, as it has been shown that intracellular ATP is decreased after fructose loading. Furthermore, we studied serum T4 tracer disappearance curves in four human subjects before and after intravenous fructose loading. In the perfused rat liver, we found a decrease in liver ATP concentration and a decrease in medium T4 disappearance and T4 uptake in the liver pool after fructose. Furthermore, it was shown that, when corrected for differences in the medium free hormone concentration, only transport to the metabolizing liver pool was decreased after fructose perfusion, whereas uptake in the nonmetabolizing pool was unaffected. Disposal, corrected for differences in transport into the metabolizing pool, was also not affected after fructose. In the human studies, intravenous fructose administration induced a rise in serum lactic acid and uric acid, indicating a decrease in liver ATP. This was observed concomitant with a decrease in serum tracer T4 disappearance during the first 3 h after fructose administration. These results suggest ATP dependence of transport of iodothyronines into the liver in vivo and show that, in the rat liver and in humans, uptake of T4 may be regulated by intracellular energy stores; in this way the tissue uptake process may affect intracellular metabolism and bioavailability of thyroid hormone.

Adenosine Triphosphate↗
PubMed1994

Growth control of primary culture hepatocytes by nonparenchymal liver cells. Role of interferon produced by liver sinusoidal cells.

Using the primary culture of liver cells, we showed that interferon produced by nonparenchymal liver cells inhibits the proliferation of cultured parenchymal liver cells. DNA synthesis of parenchymal liver cells was suppressed not only by their coculture with nonparenchymal liver cells but also by the addition of the culture supernatant of nonparenchymal liver cells. The suppressive activity of the supernatant correlated closely with the interferon (alpha + beta) level in the supernatant and was reduced by anti interferon (alpha + beta) serum. Furthermore, purified interferon (alpha + beta) also suppressed parenchymal liver cell proliferation in a dose-dependent manner and the suppression was released by anti interferon (alpha + beta) serum. The interferon level of the supernatant necessary for suppressing parenchymal liver cell proliferation, however, was extraordinarily low compared with purified interferon. The possibility exists that IFN in the culture supernatant of nonparenchymal liver cells works synergistically with other factors in the supernatant to suppress the cell proliferation.

Animals↗
PubMed1996

Characterization of brimonidine metabolism with rat, rabbit, dog, monkey and human liver fractions and rabbit liver aldehyde oxidase.

1. In vitro metabolism of 14C-brimonidine by the rat, rabbit, dog, monkey and human liver fractions was studied to assess any species differences. In vitro metabolism with rabbit liver aldehyde oxidase and human liver slices, and in vivo metabolism in rats were also investigated. The hepatic and urinary metabolites were characterized by liquid chromatography and mass spectrometry. 2. Up to seven, six, 11 and 14 metabolites were detected in rat liver S9 fraction, human liver S9 fraction, human liver slices and rat urine respectively. Rabbit liver aldehyde oxidase catalysed the metabolism of brimonidine to 2-oxobrimonidine and 3-oxobrimonidine, and further oxidation to the 2,3-dioxobrimonidine. Menadione inhibited the liver aldehyde oxidase-mediated oxidation. 3. Hepatic oxidation of brimonidine to 2-oxobrimonidine, 3-oxobrimonidine and 2,3-dioxobrimonidine was a major pathway in all the species studied, except the dog whose prominent metabolites were 4',5'-dehydrobrimonidine and 5-bromo-6-guanidinoquinoxaline. 4. These results indicate extensive hepatic metabolism of brimonidine and provide evidence for aldehyde oxidase involvement in brimonidine metabolism. The species differences in hepatic brimonidine metabolism are likely related to the low activity of dog liver aldehyde oxidase. The principal metabolic pathways of brimonidine are alpha(N)-oxidation to the 2,3-dioxobrimonidine, and oxidative cleavage of the imidazoline ring to 5-bromo-6-guanidinoquinoxaline.

Acetates↗
PubMed1991

Relationship of liver and skeletal muscle IGF-1 mRNA to plasma GH profile, production of IGF-1 by liver, plasma IGF-1 concentrations, and growth rates of cattle.

Growth hormone (GH), insulin-like growth factor-1 (IGF-1), and thyroid hormone (T3 and T4) concentrations in blood plasma of 18 crossbred cattle (six bulls, six steers, and six heifers) were measured over an 8-hr period. One week later at slaughter, IGF-1 production by liver slices and IGF-1 mRNA concentrations in skeletal muscle and liver were measured. Bulls had higher (P less than 0.05) mean plasma GH and GH peak amplitudes (P less than 0.01) than heifers, and values for steers were intermediate between bulls and heifers. Baseline GH concentrations and number of GH peaks were not significantly different for the three groups. Bulls had 1.6-fold (P less than 0.01) and 3.0-fold (P less than 0.01) greater liver IGF-1 mRNA concentrations than steers or heifers, respectively, whereas the steers had 1.8-fold (P less than 0.05) greater IGF-1 mRNA in liver than heifers. Production of IGF-1 by liver slices was greater (P less than 0.05) in bulls than steers or heifers. Bulls had 1.3-fold greater plasma IGF-1 than steers (P less than 0.01), whereas steers had 1.8-fold greater plasma IGF-1 than heifers (P less than 0.01). There were no significant differences in concentrations of skeletal muscle IGF-1 mRNA between the three groups of animals. Liver IGF-1 mRNA, liver IGF-1 production, and plasma IGF-1 were all significantly correlated with gain and mean GH peak amplitude, but not with GH baseline, GH peak frequency, or concentrations of T3 and T4. Concentrations if IGF-1 mRNA in skeletal muscle were not correlated to gain or any parameter of the GH profile. Plasma concentrations of T3 were significantly (P less than 0.05) negatively correlated to plasma GH baseline concentrations. Muscle IGF-1 mRNA concentration was negatively related to plasma T4 and T3. The results of this study suggest that the cascade of events starting with secretion of GH from the pituitary, expression of liver IGF-1 mRNA, and secretion of IGF-1 by the liver are important phenomena for growth of cattle.

Animals↗
PubMedDate not supplied

Radiofrequency ablation of rabbit liver in vivo: effect of the pringle maneuver on pathologic changes in liver surrounding the ablation zone.

OBJECTIVE: We wished to evaluate the effect of the Pringle maneuver (occlusion of both the hepatic artery and portal vein) on the pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone in rabbit livers. MATERIALS AND METHODS: Radiofrequency (RF) ablation zones were created in the livers of 24 rabbits in vivo by using a 50-W, 480-kHz monopolar RF generator and a 15-gauge expandable electrode with four sharp prongs for 7 mins. The tips of the electrodes were placed in the liver parenchyma near the porta hepatis with the distal 1 cm of their prongs deployed. Radiofrequency ablation was performed in the groups with (n=12 rabbits) and without (n=12 rabbits) the Pringle maneuver. Three animals of each group were sacrificed immediately, three days (the acute phase), seven days (the early subacute phase) and two weeks (the late subacute phase) after RF ablation. The ablation zones were excised and serial pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone were evaluated. RESULTS: With the Pringle maneuver, portal vein thrombosis was found in three cases (in the immediate [n=2] and acute phase [n=1]), bile duct dilatation adjacent to the ablation zone was found in one case (in the late subacute phase [n=1]), infarction adjacent to the ablation zone was found in three cases (in the early subacute [n=2] and late subacute [n=1] phases). None of the above changes was found in the livers ablated without the Pringle maneuver. On the microscopic findings, centrilobular congestion, sinusoidal congestion, sinusoidal platelet and neutrophilic adhesion, and hepatocyte vacuolar and ballooning changes in liver ablated with Pringle maneuver showed more significant changes than in those livers ablated without the Pringle maneuver (p < 0.05) CONCLUSION: Radiofrequency ablation with the Pringle maneuver created more severe pathologic changes in the portal vein, bile ducts and liver parenchyma surrounding the ablation zone compared with RF ablation without the Pringle maneuver. Therefore, we suggest that RF ablation with the Pringle maneuver should be performed with great caution in order to avoid unwanted thermal injury.

Animals↗
PubMed2000

Lecithin:retinol acyltransferase from mouse and rat liver. CDNA cloning and liver-specific regulation by dietary vitamin a and retinoic acid.

Lecithin:retinol acyltransferase (LRAT), present in microsomes, catalyzes the transfer of the sn-1 fatty acid of phosphatidylcholine to retinol bound to a cellular retinol-binding protein. In the present study we have cloned mouse and rat liver LRAT cDNA and tested the hypothesis that LRAT mRNA, like LRAT activity, is regulated physiologically in a liver-specific manner. The nucleotide sequences of mouse and rat liver LRAT cDNA each encode a 231-amino acid protein with 94% similarity between these species, and approximately 80% similarity to a cDNA for LRAT from human retinal pigment epithelium. Expression of rat LRAT cDNA in HEK293T cells resulted in functional retinol esterification and storage. RNA from several rat tissues hybridized with liver LRAT cDNA. However, LRAT mRNA was virtually absent from the liver of vitamin A-deficient animals, while being unaffected in intestine and testis. LRAT mRNA was rapidly induced by retinoic acid (RA) in liver of vitamin A-deficient mice and rats (P < 0.01). LRAT mRNA and enzymatic activity were well correlated in the same livers of rats treated with exogenous RA (r = 0.895, P < 0.0001), and in a dietary study that encompassed a broad range of vitamin A exposure (r = 0.799, P < 0.0001). Liver total retinol of <100 nmol/g was associated with low LRAT expression (<33% of control). We propose that RA, derived exogenously or from metabolism, serves as an important signal of vitamin A status. The constitutive expression of liver LRAT during retinoid sufficiency would serve to divert retinol into storage pools, while the curtailment of LRAT expression in retinoid deficiency would maintain retinol for secretion and delivery to peripheral tissues.

Acyltransferases↗
PubMed2002

[Dynamic expression of tenascin in rat liver during liver fibrogenesis induced by CCl(4)].

OBJECTIVE: To study the expression of tenascin in normal and fibrotic rat liver. METHODS: Liver fibrosis induced in rat with CCl(4) were divided into three stages: the stage of hepatic injury (4 weeks), early stage of hepatic fibrosis (8 weeks) and later stage of hepatic fibrosis (12 weeks). Tenascin expression in liver tissue was observed by immunohistochemical method and in situ hybridization using digoxigenin-labelled DNA probe. RESULTS: In normal rat liver there was a weak staining for tenascin. In both liver injury stage and early stage of hepatic fibrosis, both mRNA signal and immunostaining for tenascin were significantly increased as compared to that in normal liver. In later stage of hepatic fibrosis, mRNA signal and immunostaining for tenascin were decreased compared with that in early stage of hepatic fibrosis. The cellular source of tenascin in liver mainly restricted in mesenchymal cells. CONCLUSIONS: Tenascin is a component of the extracellular matrix of liver tissue. Plays a role in early matrix organization during liver fibrogenesis.

Animals↗
PubMedDate not supplied

Hemostatic modulation with the liver dialysis device in humans with advanced liver disease.

BACKGROUND/AIMS: To determine the alterations in coagulation and fibrinolysis occurring in patients treated with the liver dialysis device. METHODOLOGY: Patients with advanced liver disease treated with the liver dialysis device were studied immediately before and after the liver dialysis device treatment. SETTING: A university hospital intensive care unit. PATIENTS: Thirteen consecutive patients with advanced liver disease being evaluated for or awaiting liver transplantation. INTERVENTION: 4-6 hours of liver dialysis treatment for management of hepatic encephalopathy. OUTCOME MEASURES: A panel of coagulation and anticoagulation factors, as well as fibrinolytic and anti-fibrinolytic factors plus measures of activation of inflammation and soluble adhesion factors. RESULTS: The liver dialysis device used was found to be associated with activation of both coagulation and fibrinolytic pathways, activation of inflammation reactants, and an increase in sL-selectin levels. CONCLUSIONS: Liver dialysis device activates both coagulant and fibrinolytic pathways, activates inflammatory response, but these responses are limited to the vascular compartment by an increase in sL-selectin levels.

Aged↗
PubMedDate not supplied

The apoptotic response of liver and colorectal liver metastases to focal hyperthermic injury.

BACKGROUND: Ablation of liver tumours by focal hyperthermia causes tissue injury not only by direct effects, but also by progressive tissue damage following the initial heat application. The mechanism by which this progressive injury occurs remains undefined. Stimulation of apoptosis following the initial heat stimulus may be involved in this progression. The role of apoptosis in the subsequent progression of focal hyperthermia injury was investigated in liver and colorectal liver metastases in a murine model. MATERIALS AND METHODS: Focal hyperthermia produced by laser (Nd-YAG--wavelength 1064 nm) was applied to the liver and colorectal liver metastases in CBA mice (2 Watts for 50 seconds). The animals were killed at 0, 12, 24, 48, 72, 120 and 168 hours after the application of focal hyperthermia. Haematoxylin and eosin staining and immunohistochemistry were performed on paraffin sections to assess the extent of tissue necrosis. Apoptosis was examined by assessment of DNA fragmentation using terminal deoxynucleotidyl transferase d-uridine triphosphate nick end labelling (TUNEL) and activated Caspase 3 immunostaining. The sequence of the apoptotic response was determined at the treated tissue margins and compared to untreated liver and tumour. RESULTS: Focal hyperthermia produced progressive tissue injury in both liver and colorectal liver metastases. TUNEL labelling was less specific than activated Caspase 3 in detecting apoptotic cells. Apoptosis was detected and peaked at 12 hours following therapy based on activated Caspase 3 staining, before returning to baseline at 72 hours. In tumour tissue, the apoptotic response was more sustained, peaking at 24 hours before returning to baseline levels by 96 hours following therapy. CONCLUSION: Increased apoptosis occurs following the application of focal hyperthermia to normal liver and colorectal metastases. The apoptotic response is more sustained in tumour tissue and contributes to the progressive injury that is evident after the initial heat stimulus.

Animals↗
PubMed1991

Orthotopic liver transplantation for life-threatening veno-occlusive disease of the liver after allogeneic bone marrow transplant.

Veno-occlusive disease (VOD) of the liver is a serious and often lethal sequela to bone marrow transplantation. Although a history of prior hepatitis moderately increases the risk of VOD, reliable screening methods for identifying high risk patients are not available. New approaches to managing patients who develop serious VOD are needed. One approach may be the use of orthotopic liver transplantation in selected patients who are likely to die of the disease. In this report we describe a patient who underwent liver transplantation for life-threatening VOD following allogeneic transplantation for CML. Although this patient died early from interstitial pneumonitis, the orthotopic liver functioned well up to her death. Other reports describing successful liver transplants in patients with advanced VOD or graft-versus-host disease of the liver are discussed and the possible indications for liver transplantation for VOD after marrow transplantation are considered. Taken together, these reports suggest that orthotopic liver transplantation may be a feasible and potentially effective approach to managing select patients with life-threatening liver dysfunction after marrow transplantation.

Adult↗
PubMed1979

[Histologic study of the teleost liver. I. The structure of the liver parenchyma].

The liver parenchyma of the teleosts investigated in this study does not show a true lobular pattern. The finer arrangement of the hepatocytes corresponds to the classical conception that the structure of the liver parenchyma is tubular. On the other hand the laminar structure of parenchyma (ELIAS), as it is often described in the more recent literature, must be regarded as a predominantly descriptive perspective. Remnants of a tubular structure also appear in the liver of the cyprinids investigated here, which have no real liver tubules owing to the special feature of the canalicular region (unicellular or "intracellular" bile canaliculi). Compared to the liver of higher vertebrates eight of the nine teleost species investigated here possess a liver poor in connective tissue. The liver of Haplochromis burtoni also lacks a continuous tissue layer beneath the peritoneal mesothelium. In contrast the liver of Tetraodon leiurus is characterized by an abundance of connective tissue. This phenomenon can be attributed to the high proportion of sinusoids in the parenchyma, which confers a structure similar to that of mammalian liver. The resulting loss of mechanical stability is obviously compensated for by the enlarged contribution of the connective tissue to the structure of the parenchyma.

Animals↗
PubMed1981

p-Chloro-N-methylaniline demethylase activity in liver and extrahepatic tissues of the human fetus and in chick embryo liver.

We achieved a 50-fold increase in sensitivity of a fluorescence assay for p-chloro-N-methylaniline (p-CNMA) demethylase enabling us to examine the kinetics of the reaction in chick embryo liver and human fetal tissues and its inducibility in chick embryo liver. In chick embryo liver, p-CNMA demethylase activity was maximally induced (to about 200% of control levels) by both phenobarbital and beta-naphthoflavone. p-CNMA demethylase is therefore nonselective in its response to inducers of the P-450 and P-448 classes, respectively. Line-weaver-Burk plots of the data suggest that single kinetic components predominated in the reaction for both control and induced livers (mean apparent KmS: control, 3.8 X 10(-5) M; phenobarbital treated, 3.8 X 10(-5) M). Differences in the KmS and the pH-activity curves for the phenobarbital- and beta-naphthoflavone-induced enzymes suggested, however, that the induced enzymes were not identical. p-CNMA demethylase activity was measurable in liver and extrahepatic organs of the human fetus and was 1.5 times higher in human fetal liver than in chick embryo liver. At least two kinetic components participated in the reaction in the human liver. Reaction rates in human fetal adrenal, lung and brain were about 60, 2 and 1% of the liver rates, respectively. Detection of mixed function oxidase activity in human fetal brain, not usually considered a site of biotransformation, suggests that the fetal brain could be a site of cytotoxic activation of chemicals during human fetal development.

Animals↗
PubMed1995

Sites of biotransformation for the cyclosporin derivative SDZ IMM 125 using human liver and kidney slices and intestine. Comparison with rat liver slices and cyclosporin A metabolism.

SDZ IMM 125 (IMM), the hydroxyethyl derivative of cyclosporin A (CSA), is metabolized by human liver slices to analogous primary metabolites, hydroxylated IMM1 and IMM9 and N-demethylated IMM4N, as for CSA (M17/AM1, M1/AM9, and M21/AM4N), but the rate and extent of IMM biotransformation is less than for CSA. Initial rates of IMM metabolite formation in the human liver slice cultures are 6.6 +/- 2.8 nmol/hr/g liver at 1 microM IMM and 24.3 +/- 22.9 nmol/hr/g liver at 10 microM IMM, whereas the rate of CSA metabolite formation is 1.8-fold faster at both concentrations. The percentage of unchanged IMM is 73% at 1 microM and 80% at 10 microM after 24 hr, reflecting the lower extent of IMM metabolism, about one-third (1 microM) and one-half (10 microM) that of CSA. In rat liver slices, IMM is metabolized to the same primary metabolites as in human liver slices, but more slowly and remains 90% unchanged at 24 hr. Human jejunum formed the same primary metabolites of IMM and CSA as in liver. Upscaling the slice rate of biotransformation revealed that human jejunum would contribute considerably to the first-pass of IMM and CSA, being approximately 2 to 3-fold slower than the rate in liver. The inhibition of both IMM and CSA biotransformation by triacetyloleandomycin implicates the involvement of cytochrome P4503A proteins. Human kidney cortex slices metabolized IMM to IMM1 and IMM9, accounting for approximately 75% of the total metabolites. Total metabolite formation represented approximately 64% of liver metabolite formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗