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Objectives: During fasting, liver pivotally regulates blood glucose levels through glycogenolysis and gluconeogenesis. Kidney also produces glucose through gluconeogenesis. Gluconeogenic genes are transactivated by fasting, but their expression patterns are chronologically different between the two organs. We find that renal gluconeogenic gene expressions are positively correlated with the blood β-hydroxybutyrate concentration. Thus, we herein aim to investigate the regulatory mechanism and its physiological implications., Methods: Gluconeogenic gene expressions in liver and kidney were examined in hyperketogenic mice such as high-fat diet (HFD)-fed and ketogenic diet-fed mice, and in hypoketogenic PPARα knockout (PPARα -/- ) mice. Renal gluconeogenesis was evaluated by rise in glycemia after glutamine loading in vivo. Functional roles of β-hydroxybutyrate in the regulation of renal gluconeogenesis were investigated by metabolome analysis and RNA-seq analysis of proximal tubule cells., Results: Renal gluconeogenic genes were transactivated concurrently with blood β-hydroxybutyrate uprise under ketogenic states, but the increase was blunted in hypoketogenic PPARα -/- mice. Administration of 1,3-butandiol, a ketone diester, transactivated renal gluconeogenic gene expression in fasted PPARα -/- mice. In addition, HFD-fed mice showed fasting hyperglycemia along with upregulated renal gluconeogenic gene expression, which was blunted in HFD-fed PPARα -/- mice. In vitro experiments and metabolome analysis in renal tubular cells showed that β-hydroxybutyrate directly promotes glucose and NH 3 production through transactivating gluconeogenic genes. In addition, RNA-seq analysis revealed that β-hydroxybutyrate-induced transactivation of Pck1 was mediated by C/EBPβ., Conclusions: Our findings demonstrate that β-hydroxybutyrate mediates hepato-renal interaction to maintain homeostatic regulation of blood glucose and systemic acid-base balance through renal gluconeogenesis regulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

The biliary epithelial cells (cholangiocytes) in the liver originate from undifferentiated liver parenchymal cells (hepatoblasts) that are located adjacent to the portal vein. This differentiation process is driven by Notch signaling, which is recognized for generating salt-and-pepper (fine-grained) patterns, in contrast to one- or two-cell layer (spatially confined) patterning in cholangiocyte differentiation. It is unclear how Notch signaling acts and localizes only in cholangiocytes. A computer simulation study suggested that low production rates of the ligands or receptors of Notch signaling are crucial for the spatially confined patterning, although biochemical examination is lacking. Here, we analyzed a publicly available single-cell ATAC-sequencing dataset from human fetal liver samples. We showed high chromatin accessibility for the ligands only in vascular cells, while that for the receptor is limited to a small population of hepatoblasts. This finding strengthens the previously proposed idea that low production rates of the ligands or receptors of Notch signaling enable vascular induction of cholangiocytes., (© 2023. The Author(s).)

Macrophages play an indispensable role in both innate and acquired immunity, while the persistence of activated macrophages can sometimes be harmful to the host, resulting in multi-organ damage. Macrophages develop from monocytes in the circulation. However, little is known about the organ affinity of macrophages in the normal state. Using in vivo imaging with XenoLight DiR®, we observed that macrophages showed strong affinity for the liver, spleen and lung, and weak affinity for the gut and bone marrow, but little or no affinity for the kidney and skin. We also found that administered macrophages were still alive 168 hours after injection. On the other hand, treatment with clodronate liposomes, which are readily taken up by macrophages via phagocytosis, strongly reduced the number of macrophages in the liver, spleen and lung., Competing Interests: The authors have declared that no competing interests exist.

We evaluated the changes of gadoxetic acid uptake of the liver parenchyma after hepatitis C virus (HCV) eradication by direct-antiviral agent (DAA) therapy. The increase rate of the liver-to-muscle signal intensity ratio, the skewness and the kurtosis were calculated in the hepatobiliary phase. After sustained virological response, gadoxetic acid uptake of the liver parenchyma increased, but became heterogeneous. Our study proved that HCV eradication by DAA therapy could significantly affect gadoxetic acid uptake.

Purpose: To demonstrate the relative importance of organic anion-transporting polypeptides (OATPs) and cytochrome P450 3A (CYP3A) in the hepatic elimination of substrate drugs., Methods: A cocktail of subtherapeutic doses of bosentan, repaglinide, clarithromycin, darunavir, simeprevir, and midazolam (CYP3A probe) was administered orally to eight healthy volunteers. Rifampicin (OATP inhibitor; 600 mg, p.o.) and itraconazole (CYP3A inhibitor; 200 mg, i.v.) were coadministered with the cocktail in the second and third phases, respectively. Based on the extended clearance concept, in vivo β values (fraction of metabolism plus biliary excretion among all the intracellular fates of drugs including basolateral efflux) and R dif values (ratio of diffusional uptake to active uptake) were estimated., Results: Rifampicin increased plasma AUCs of bosentan (×3.2), repaglinide (×1.9), clarithromycin (×1.9) and simeprevir (×7.2). Itraconazole increased those of clarithromycin (×2.3), simeprevir (×2.2) and midazolam (×3.7), which had relatively small β values. The plasma AUC of bosentan (with relatively large β and small R dif ) was dominated by OATP-mediated uptake. The AUC of simeprevir was also dominated by OATP-mediated uptake because of its small R dif value., Conclusions: The DDI study clarified the rate-determining processes of OATP/CYP3A substrates. Our analyses provide valuable information for predicting complex drug-drug interactions involving multiple processes.

Aldehyde reductase (AKR1A) plays a role in the biosynthesis of ascorbic acid (AsA), and AKR1A-deficient mice produce about 10-15% of the AsA that is produced by wild-type mice. We found that acetaminophen (AAP) hepatotoxicity was aggravated in AKR1A-deficient mice. The pre-administration of AsA in the drinking water markedly ameliorated the AAP hepatotoxicity in the AKR1A-deficient mice. Treatment of the mice with AAP decreased both glutathione and AsA levels in the liver in the early phase after AAP administration, and an AsA deficiency delayed the recovery of the glutathione content in the healing phase. While in cysteine supply systems; a neutral amino acid transporter ASCT1, a cystine transporter xCT, enzymes for the transsulfuration pathway, and autophagy markers, were all elevated in the liver as the result of the AAP treatment, the AsA deficiency suppressed their induction. Thus, AsA appeared to exert a protective effect against AAP hepatotoxicity by ameliorating the supply of cysteine that is available for glutathione synthesis as a whole. Because some drugs produce reactive oxygen species, resulting in the consumption of glutathione during the metabolic process, the intake of sufficient amounts of AsA would be beneficial for protecting against the hepatic damage caused by such drugs., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Re-do coronary artery bypass grafting to the right coronary artery via the diaphragm is useful, especially when re-sternotomy may injure a patent internal thoracic artery graft under the sternum. When the target vessel is located on the posterior wall of the heart, however, anastomosis becomes difficult. In our case, we mobilized the liver from the diaphragm and divided the diaphragm more posteriorly. The gastroepiploic artery was successfully anastomosed to the target vessel.

Purpose: To evaluate if Gd-EOB-DTPA-enhanced MRI could identify liver tissue damage caused by radiation exposure in patients undergoing external beam radiation therapy., Materials and Methods: We enrolled 11 patients who underwent Gd-EOB-DTPA-enhanced MRI during or after radiotherapy in which the radiation field included the liver. External beam radiotherapy was delivered through multiple fields using a 10-MV linear accelerator. The hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI were qualitatively evaluated for the presence of a decreased uptake of Gd-EOB-DTPA in the irradiated area in the liver. Next, signal intensity (SI) ratio of the irradiated area to the non-irradiated liver parenchyma was also calculated. The absorbed dose of the irradiated area in the liver was standardized using equivalent dose in 2Gy fraction (EQD2) and biological effective dose (BED). The results of qualitative analysis were compared with EQD2 or BED, and linear regression analysis was performed between EQD2 or BED and SI ratio., Results: Twenty-two irradiated areas were evaluated. Qualitative analysis revealed a decreased uptake of Gd-EOB-DTPA in 14 areas and no decreased uptake of Gd-EOB-DTPA in eight areas. The thresholds of EQD2 and BED causing a decreased uptake of Gd-EOB-DTPA were considered to be 24 to 29Gy and 29 to 35Gy, respectively. Quantitatively, SI ratio decreased as EQD2 or BED increased (r=0.89, p<0.001), and the inverse relationship between signal enhancement and the absorbed dose in the irradiated area was obtained. One area with EQD2 of 50Gy and BED of 60Gy showed a slightly decreased uptake of Gd-EOB-DTPA on the 40th day but a clearly decreased uptake of Gd-EOB-DTPA on the 123rd day from initiation of radiotherapy., Conclusions: Gd-EOB-DTPA-enhanced MRI described RLI as a decreased uptake of Gd-EOB-DTPA matching the irradiated area. The occurrence of this finding was significantly correlated with the absorbed dose of the irradiated area in the liver., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The purpose of this study was to determine the utility of triple-phase helical computed tomography (CT) for differentiating canine hepatic masses. Seventy dogs with hepatic masses underwent triple-phase CT followed by surgical removal of the hepatic masses. Triple-phase helical CT scans for each dog included precontrast, arterial phase, portal venous phase, and delayed phase studies. The removed hepatic masses were histopathologically classified as hepatocellular carcinoma (n = 47), nodular hyperplasia (n = 14), and hepatic metastatic tumors (n = 9) in dogs. Of the 47 hepatocellular carcinomas, the most common CT findings included a heterogeneous pattern with hyper-, iso-, and hypoenhancement in both the arterial and portal venous phases (40/47, 85.1%). Of the 14 nodular hyperplasias, the most common CT findings were a homogeneous pattern with hyper- and isoenhancement in both the portal venous and delayed phases (13/14, 92.9%). Of nine hepatic metastatic tumors, the most common CT findings included a homogeneous hypoenhancement pattern in both the arterial and portal venous phases (8/9, 88.9%). In addition, 5 (55.6%) showed homogeneous hypoenhancement patterns in the delayed phase. Findings from our study indicated that triple-phase CT is a useful tool for preoperative differentiation of hepatocellular carcinoma, nodular hyperplasia, and hepatic metastatic tumors in dogs., (© 2013 American College of Veterinary Radiology.)

Many biological activities of green tea have been attributed to a major constituent, (minus;)-epigallocatechin gallate (EGCG). We previously reported that EGCG and an EGCG-free fraction derived from green tea modulated the gene expression of gluconeogenic enzymes, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, in the mouse liver. EGCG is also known to affect the gene expression of enzymes related to lipid metabolism. However, it remains to be examined whether or not a constituent other than EGCG contributes to the change in gene expression of these enzymes. In this study, we prepared an EGCG-free water-soluble fraction (GT-W), and examined its effects on the hepatic gene expression of lipogenic enzymes in mice. The results of quantitative real-time PCR assays indicated that the dietary administration of GT-W for 4 weeks reduced the hepatic gene expression of lipogenic enzymes: fatty acid synthase, hydroxymethylglutaryl coenzyme A reductase, and acetyl-coenzyme A carboxylase alpha. Also, the gene expression of sterol regulatory element-binding transcription factor (Srebf)1 and/or Srebf2 was reduced, suggesting that the reduction of Srebfs contributed to the down-regulation of the lipogenic enzymes, since these transcription factors bind the promoter region to enhance their expression. The plasma levels of triglycerides and cholesterol were reduced with statistical significance in the group given a diet containing GT-W. These results suggest that in addition to EGCG, green tea contains some component(s) which may help to prevent arteriosclerosis and obesity.

We previously reported that social isolation stimulated a stress response leading to increasing plasma corticosterone level and disruption of the hepatic lipid metabolism-related pathway, without changing body and organ weights, in mice after 4 weeks of social isolation stress, compared with the grouped-housing control (5 mice/cage). In this study, we evaluated the effects of social isolation stress for an extended period on physiologic changes in male C57BL/6J mice. Plasma corticosterone was reduced after 13 weeks, indicating mice might adapt to social isolation stress. However, body and visceral fat weights were significantly increased in combination with hepatic hypertrophy, and significant decreases in levels of triglyceride and adiponectin in plasma were observed. In conclusion, it is tempting to speculate that mice exposed to social isolation stress for 13 continuous weeks could be at an increased risk of overweight with hepatic hypertrophy. Our results also imply that physiological changes, at least fatty acid metabolism, under stress exposure might be an important factor when evaluating the chronic effects of environmental chemicals.

Hepatic surface enhancement on CT can represent particular clinical significance in various abdominal conditions, at times being the only abnormality found. Detecting hepatic surface enhancement, together with the other ancillary diagnostic techniques as well, may lead to grasp of the underlying condition and to early or timely diagnosis and treatment of abdominal disorders. This manuscript describes the spectrum of hepatic surface enhancement on CT, and the importance of focusing on the hepatic surface during interpretation is emphasized.

Chinese herbal medicines, Inchinko-to, Bofu-tsusho-san and Dai-saiko-to, containing 3, 18 and 8 components, respectively, have since long been used as an anti-inflammatory, antipyretic, choleretic and diuretic agent for liver disorders and jaundice, as an anti-obesity agent, a hypocholesterolemic agent for liver disorders and a therapeutic and/or preventive agent for cholesterol gallstone disease with hypertriglycerid-emia in China and Japan, respectively. In the present study, we investigated the effects of these three herbal medicines in young male mice fed a high-fat diet. Plasma levels of lipids and the numbers of the fatty droplets in the liver cytoplasm were markedly lowered by the diets supplemented with three herbal medicines. The liver weights and the body growth were reduced by the diet supplemented with Dai-saiko-to, which slightly affected the concentrations of total protein, albumin, creatinine or calcium, and the activity of lactate dehydrogenase. Thus, Dai-saiko-to, besides Bofu-tsusho-san, seems effective in the activities of anti-obesity, anti-hyperlipidemia and anti-hyperlipids in liver cytoplasm, when used carefully.

A role of natural killer T (NKT) cells in transplant rejection remains unknown. Here, we determined whether NKT cells participate in rejection of islet allografts, using NKT cell-deficient mice. Survival of islet allografts in streptozotocin-induced diabetic CD1d(-/-) mice or Valpha14 NKT cell(-/-) mice was significantly prolonged without immunosuppression when grafted into the liver, but not beneath the kidney capsule, compared with wild-type mice. Acceptance of intrahepatic islet allografts was achieved in CD1d(-/-) mice by a subtherapeutic dose of rapamycin, which was abrogated in conjunction with the transfer of hepatic mononuclear cells from wild-type, but not from CD1d(-/-), mice at islet transplantation. The second islet grafts from a donor-specific, but not from a third-party, strain in CD1d(-/-) mice bearing functional islet allografts were accepted without immunosuppression at 120 days after the initial transplantation. These findings demonstrate that NKT cells play a significant role in rejection of islet allografts in the liver of mice, but that NKT cells are not essential for induction of donor-specific unresponsiveness in this model. The current study indicates that NKT cells might be considered as a target for intervention to prevent islet allograft rejection when the liver is the site of transplantation.

The purpose of this study was to analyze computed tomographic (CT) findings of hepatic lesions due to Ascaris suum infection. CT of the liver in three patients, all of whom had immunoserologically confirmed A. suum infection, were retrospectively reviewed. Twenty-five lesions were identified in total. Two radiologists analyzed CT findings in a consensus fashion, with particular interest in the margin, shape, and location of the lesions. Hepatic lesions were ill-defined (22 of 25), small (3-35 mm; average, 11 mm), and nodular (18 of 25) or wedge (three of 25) in shape. Most were located in periportal (16 of 25) or subcapsular (six of 25) regions. Hepatic nodules due to visceral larva migrans of A. suum were located mainly in periportal or subcapsular regions, which may represent periportal eosinophilic granuloma, its pathologic feature. The results were considered to represent the pathophysiology of this entity.

Fitz-Hugh-Curtis syndrome (FHCS) is a condition with right upper quadrant pain in association with pelvic inflammatory disease. Invasive procedures such as laparoscopy or laparotomy were indispensable to definite diagnosis of FHCS, and no more useful methods in radiological diagnosis of FHCS has been reported until now. In this present study abdominal enhanced-CT findings were analysed retrospectively in eight cases diagnosed clinically as FHCS. We focused on hepatic capsular enhancement, which was identified on early phase in all cases and on delayed phase in five. Moreover, hepatic capsular enhancement was detected at the anterior surface of medial segment and the lateral aspect of right lobe in all cases, while at the anterior surface of lateral segment in five cases. These findings, which disappeared on follow-up CT after treatment, were thought to reflect "acute" peri-hepatitis. Abdominal enhanced CT, especially on early phase, is suggested to be a non-invasive, useful modality for the diagnosis of FHCS. When hepatic capsular enhancement is identified in the interpretation of abdominal enhanced CT images in sexually active women who have right upper abdominal pain, we should suspect the possibility of FHCS and examine gynecological findings or the value of IgA and IgG antibodies for Chlamydia trachomatis.

The reductive-oxidative status of tissues regulates the expression of many inflammatory genes that are induced during gram-negative bacterial infections. The cytokine gamma interferon (IFN-gamma) is a potent stimulus for host inflammatory gene expression, and oxidative stress has been shown to inhibit its production in mice challenged with Escherichia coli bacteria. The objective of the present study was to characterize the cells that produced IFN-gamma in a mouse bacterial peritonitis model and determine the effects of oxidative stress on their activation. The liver contained large numbers of IFN-gamma-expressing lymphocytes following challenge with viable E. coli bacteria. The surface phenotypes of IFN-gamma-expressing hepatic lymphocytes were those of natural killer (NK) cells (NK1.1(+) CD3(-)), conventional T cells (NK1.1(-) CD3(+)), and NK T cells (NK1.1(+) CD3(+)). Treating mice with diethyl maleate to deplete tissue thiols significantly impaired IFN-gamma production by NK cells, conventional T cells, and CD1d-restricted NK T cells in response to E. coli challenge. However, IFN-gamma expression by a subset of NK T cells, which did not bind alpha-galactosylceramide-CD1d tetramers, was resistant to the inhibitory effects of tissue oxidative stress. Stress-resistant IFN-gamma-expressing cells were also predominantly CD8(+) and bore gamma delta T-cell antigen receptors. The residual IFN-gamma response by NK T cells may explain previous reports of hepatic gene expression following gram-negative bacterial challenge in thiol-depleted mice. The finding also demonstrates that innate immune cells differ significantly in their responses to altered tissue redox status.

We present CT findings of a 22-year-old woman diagnosed as Fitz-Hugh-Curtis syndrome. The patient was admitted to our hospital with right upper abdominal pain. Abdominal enhanced CT showed hepatic capsular enhancement over the medial segment and the right lobe on the early phase. This capsular enhancement completely disappeared after treatment. Abdominal enhanced CT may serve as a non-invasive modality for the diagnosis of Fitz-Hugh-Curtis syndrome.

A case with a pseudolesion associated with focal fatty deposition in segment IV of the liver observed on conventional CT and CT during arterial portography caused by the parabiliary venous drainage is presented. Close observation of the common hepatic angiography was helpful to recognize this unusual vessel as a cause of this pseudolesion. Selective catheterization of the posterior superior pancreaticoduodenal artery and CT during its venous phase confirmed the etiology of the pseudolesion.

Pancreatic islet transplantation represents a potential treatment for insulin-dependent diabetes mellitus. However, the precise cellular and molecular mechanisms of the immune reactions against allogeneic and xenogeneic transplanted islets remain unclear. Here, we demonstrate that CD4(+) Valpha14 natural killer T (NKT) cells, a recently identified lymphoid cell lineage, are required for the acceptance of intrahepatic rat islet xenografts. An anti-CD4 mAb, administrated after transplantation, allowed islet xenografts to be accepted by C57BL/6 mice, with no need for immunosuppressive drugs. The dose of anti-CD4 mAb was critical, and the beneficial effect appeared to be associated with the reappearance of CD4(+) NKT cells at around 14 days after transplantation. Interestingly, rat islet xenografts were rejected, despite the anti-CD4 mAb treatment, in Valpha14 NKT cell-deficient mice, which exhibit the normal complement of conventional lymphoid cells; adoptive transfer of Valpha14 NKT cells into Valpha14 NKT cell-deficient mice restored the acceptance of rat islet xenografts. In addition, rat islet xenografts were accepted by Valpha14 NKT mice having only Valpha14 NKT cells and no other lymphoid cells. These results indicate that Valpha14 NKT cells play a crucial role in the acceptance of rat islet xenografts in mice treated with anti-CD4 antibody, probably by serving as immunosuppressive regulatory cells.

A novel sulfotransferase was purified from the rat liver cytosol to electrophoretic homogeneity via five column chromatography steps (hydroxylapatite I, DEAE Bio-Gel, ATP-agarose I, hydroxylapatite II, and ATP-agarose II). The minimum molecular weight of the purified enzyme was determined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis to be approximately 33,000. Gel filtration chromatography revealed a native molecular weight of approximately 34,000, indicating the enzyme being present in the monomeric form. The purified sulfotransferase displayed enzymatic activities, with a pH optimum of 9.25, toward various tyrosine and 3,4-dihydroxyphenylalanine (Dopa) isomers, except DL-ortho-tyrosine. Thyroid hormones, as well as dopamine and p-nitrophenol, could also be used as substrates. The apparent Km value of the enzyme (designated the Dopa/tyrosine sulfotransferase) for L-Dopa, determined at a constant 14 microM of 3'-phosphoadenosine 5'-phosphosulfate, was 0.76 mM. The intact enzyme was found to be N-blocked when subjected to N-terminal sequencing. Three internal partial amino acid sequences, obtained by analyzing its proteolytic fragments, were found to be distinct from the homologous sequences of other known rat liver sulfotransferases. The deduced amino acid sequence of a full-length cDNA isolated from a rat liver cDNA library confirmed the identity of the Dopa/tyrosine sulfotransferase as a new type of aryl sulfotransferase. Upon transfection of COS-7 cells with an expression vector (pMSG-CMV) harboring the full-length cDNA, a 33-kDa protein displaying enzymatic and immunological properties similar to those of the purified Dopa/tyrosine sulfotransferase was expressed.

Prostaglandin (PG) specificity of two 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase isozymes, DD2 and DD4, of human liver was examined. DD2 exhibited NADPH-linked reductase activity for 9-,11- and 15-ketoprostaglandins at a pH optimum of 6.0, whereas DD4 reduced only 15-ketoprostaglandin F2 alpha. DD2 showed the highest Vmax/Km value for PGD2 of the PG substrates, and the reduced product of PGD2 was identified to 9 alpha,11 beta-PGF2 by gas chromatography-mass spectrometry. In the reverse reaction with NADP+ as a cofactor, the two enzymes slowly oxidized several PGs with 9-, 11- and/or 15-hydroxy groups, except that DD2 showed high activity for 9 alpha,11 beta-PGF2 at a pH optimum of 10.0. The Km and Vmax values of DD2 for PGD2 were 57 microM and 250 nmol/min per mg, respectively, at pH 7.0 and 37 degrees C, and the respective values for 9 alpha,11 beta-PGF2 were 72 microM and 10 nmol/min per mg. PGD2 11-ketoreductase activity in human liver cytosol was recovered in 30-75% saturated ammonium sulfate fraction. More than 77% of the PGD2 11-ketoreductase activity in the ammonium sulfate fraction was immunoprecipitated by antibodies against DD2, and inhibited by known inhibitors of the enzyme. These results suggest that DD2 is a major soluble PGD2 11-ketoreductase species in human liver.

Human liver contains two dihydrodiol dehydrogenases, DD2 and DD4, associated with 3 alpha-hydroxysteroid dehydrogenase activity. We have raised polyclonal antibodies that cross-reacted with the two enzymes and isolated two 1.2 kb cDNA clones (C9 and C11) for the two enzymes from a human liver cDNA library using the antibodies. The clones of C9 and C11 contained coding sequences corresponding to 306 and 321 amino acid residues respectively, but lacked 5'-coding regions around the initiation codon. Sequence analyses of several peptides obtained by enzymic and chemical cleavages of the two purified enzymes verified that the C9 and C11 clones encoded DD2 and DD4 respectively, and further indicated that the sequence of DD2 had at least additional 16 residues upward from the N-terminal sequence deduced from the cDNA. There was 82% amino acid sequence identity between the two enzymes, indicating that the enzymes are genetic isoenzymes. A computer-based comparison of the cDNAs of the isoenzymes with the DNA sequence database revealed that the nucleotide and amino acid sequences of DD2 and DD4 are virtually identical with those of human bile-acid binder and human chlordecone reductase cDNAs respectively.

The stereochemical course in the enzymatic oxidation of trans-dihydrodiols of benzene and naphthalene by dimeric dihydrodiol dehydrogenase of monkey kidney was compared with that by monomeric dihydrodiol dehydrogenase of rat liver. The monkey kidney and rat liver enzymes each oxidized about half of the racemic dihydrodiol of benzene added to the reaction mixture, but almost all the substrate was disappeared in the reaction mixture containing both enzymes. The CD spectra of the unreacted dihydrodiols of benzene and naphthalene in reaction mixtures containing the rat liver enzyme showed the negative sign of Cotton effect, while those in reaction mixtures containing the monkey kidney enzyme gave the positive sign of Cotton effect. Thus, the monkey kidney dimeric enzyme selectively oxidized (-)-[1R,2R]-dihydrodiols of aromatic hydrocarbons, in contrast to the stereo-specificity of the rat liver enzyme for the (+)-[1S,2S]-isomers. The (+)-[1S,2S]- and (-)-[1R,2R]-dihydrodiols of benzene were separately prepared from the racemic form by using the two enzymes, and were used as substrates to determine the stereospecificity of dihydrodiol dehydrogenases from other mammalian tissues. The dimeric enzymes from pig liver and rabbit lens also exhibited specificity for the (-)-isomer, which was opposite to that of the monomeric enzymes from human and mouse liver, although aldehyde reductase and aldose reductase oxidized both (+)- and (-)-isomers.

Dihydrodiol dehydrogenase from pig liver was inactivated by diethylpyrocarbonate (DEP) and by rose bengal-sensitized photooxidation. The DEP inactivation was reversed by hydroxylamine and the absorption spectrum of the inactivated enzyme indicated that both histidine and tyrosine residues were carbethoxylated. The rates of inactivation by DEP and by photooxidation were dependent on pH, showing the involvement of a group with a pKa of 6.4. The kinetics of inactivation and spectrophotometric quantification of the modified residues suggested that complete inactivation was caused by modification of one histidine residue per active site. The inactivation by the two modifications was partially prevented by either NADP(H) or the combination of NADP+ and substrate, and completely prevented in the presence of both NADP+ and a competitive inhibitor which binds to the enzyme-NADP+ binary complex. The DEP-modified enzyme caused the same blue shift and enhancement of NADPH fluorescence as did the native enzyme, suggesting that the modified histidine is not in the coenzyme-binding site of the enzyme. The results suggest the presence of essential histidine residues in the catalytic region of the active site of pig liver dihydrodiol dehydrogenase.

Two monomeric dihydrodiol dehydrogenases with pI values of 5.4 and 7.6 were co-purified with androsterone dehydrogenase activity to homogeneity from human liver. The two enzymes differed from each other on peptide mapping and in their heat-stabilities; with respect to the latter the dihydrodiol dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase activities of the respective enzymes were similarly inactivated. The pI 5.4 enzyme was equally active towards trans- and cis-benzene dihydrodiols, and towards (S)- and (R)-forms of indan-1-ol and 1,2,3,4-tetrahydronaphth-1-ol and oxidized the 3 alpha-hydroxy group of C19-, C21- and C24-steroids, whereas the pI 7.6 enzyme showed high specificity for trans-benzene dihydrodiol, (S)-forms of the alicyclic alcohols and C19- and C21-steroids. Although the two enzymes reduced various xenobiotic carbonyl compounds and the 3-oxo group of C19- and C21-steroids, and were A-specific in the hydrogen transfer from NADPH, only the pI 5.4 enzyme showed reductase activity towards 7 alpha-hydroxy-5 beta-cholestan-3-one and dehydrolithocholic acid. The affinity of the two enzymes for the steroidal substrates was higher than that for the xenobiotic substrates. The two enzymes also showed different susceptibilities to the inhibition by anti-inflammatory drugs and bile acids. Whereas the pI-5.4 enzyme was highly sensitive to anti-inflammatory steroids, showing mixed-type inhibitions with respect to indan-1-ol and androsterone, the pI 7.6 enzyme was inhibited more potently by non-steroidal anti-inflammatory drugs and bile acids than by the steroidal drugs, and the inhibitions were all competitive. These structural and functional differences suggest that the two enzymes are 3 alpha-hydroxysteroid dehydrogenase isoenzymes.

Localization of intravenously injected [125I]-endothelin-1 was examined in rat liver by light and electron microscopic radioautography. At 10 min after injection, silver grains were localized along the sinusoidal wall, i.e., mostly on the thin processes of fat-storing cells and sinusoidal endothelial cells, and also on the Kupffer cells and the microvilli of hepatocytes. About 35% of the total silver grains were located on the processes of fat-storing cells at 10 min. The grain density (number of silver grains/cell area) of fat-storing cells was three-fold that of Kupffer cells, and 18-fold that of hepatocytes. At 60 min, 60% of the total grains were observed on the fat-storing cells, though the value of grain density was not changed. Silver grains were internalized into the cytoplasm of fat-storing cells and often associated with multivesicular bodies. In contrast, the grain density of endothelial cells and Kupffer cells decreased with time. These results indicate that hepatic fat-storing cells have a considerable number of endothelin-binding sites, and incorporate bound endothelin into cytoplasm.

3-Deoxyglucosone reductase activity in the extracts of rat, pig and human livers was potently inhibited by aldehyde reductase inhibitors. The major species of 3-deoxyglucosone reductase purified from human and pig livers were biochemically and immunochemically identical with aldehyde reductase. The two enzymes and rat liver aldehyde reductase exhibited higher catalytic efficiency for 3-deoxyglucosone than for D-glucuronate, a representative substrate of aldehyde reductase.

The mechanism of the diminished biliary clearance of cefpiramide (CPM) in rats with obstructive jaundice (OJ) was investigated by using isolated hepatocytes. The kinetics of CPM uptake by hepatocytes isolated from normal rats and rats with OJ could be explained by the combination of saturable carrier-mediated and nonsaturable first-order rate processes. The maximum uptake rate (Vmax) of the carrier-mediated process was significantly decreased in OJ, compared with normal hepatocytes, while the Michaelis constant (Km) and the first-order rate constant (kd) were not significantly different. This result indicated that the number of CPM transport carriers was decreased in OJ hepatocytes. Further, no CPM uptake occurred from the serum of OJ rats into normal hepatocytes. Partial recovery of CPM uptake after treatment of OJ serum with activated charcoal suggested the accumulation of inhibitors of CPM uptake in OJ serum.

Two acidic and three basic forms of monomeric dihydrodiol dehydrogenase with molecular weights in the range of 36,000-39,000 were purified from human liver. One acidic enzyme (pI 5.2), which was specific for NADP- and dihydrodiols of benzene and naphthalene, was immunologically identified as aldehyde reductase. The other four enzymes oxidized alicyclic alcohols as well as the dihydrodiols using both NADP+ and NAD+ as cofactors, but showed differences in specificity for hydroxysteroids and inhibitor sensitivity. Two of the basic enzymes (pI 9.7 and 9.1) exhibited a 20 alpha-hydroxysteroid dehydrogenase activity and sensitivity to 1,10-phenanthroline, whereas the third basic enzyme (pI 7.6) oxidized some 3 alpha-hydroxysteroids at low rates and was inhibited by cyclopentane-1,1-diacetic acid. Another acidic enzyme, which accounted for the largest amount of enzyme activity in the tissue and appeared in two heterogenous forms with pI values of 5.9 and 5.4, showed a high 3 alpha-hydroxysteroid dehydrogenase activity and was the most sensitive to inhibition by medroxyprogesterone acetate. The Km values of the enzymes, except the pI 5.2 enzyme, for hydroxysteroids (10(-6) to 10(-7) M) were lower than those for xenobiotic alcohols.

Chang liver cells cultured in the simultaneous presence of novobiocin and butyrate stopped proliferating and changed into fibroblast-like cells with remarkably elongated cytoplasm. In these fibroblast-like cells, the cellular content of both protein and DNA was increased 2- to 3-fold. In addition, the production of specific proteins such as type III procollagen, actin, and tubulin was increased and the expression of proliferation-associated nuclear antigen which was reactive with Ki-67 monoclonal antibody was reduced remarkably. Therefore, Chang liver cells cultured with novobiocin and butyrate were considered to be arrested at the premitotic G2 phase of the cell cycle and then enter into the noncycling resting state. These actions of novobiocin and butyrate were not mediated by the pathway of epidermal growth factor action or modulated by the diacylglycerol agonist 1-oleoyl-2-acetylglycerol and the C kinase inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine. On the other hand, novobiocin was disclosed to be a stimulator of [3H]acetate uptake and acted synergistically with butyrate in enhancing nuclear protein acetylation. From these results it can be speculated that novobiocin and butyrate chemically modulate nuclear proteins and thereby alter the gene expression and the differentiation state of Chang liver cells.

The kinetic properties of the NADPH-dependent reduction of aromatic aldehydes and ketones catalyzed by low- and high-molecular-weight aldehyde reductases [alcohol : NADP oxidoreductase, EC 1.1.1.2] and 3 alpha- and 3 beta-hydroxysteroid dehydrogenases [EC 1.1.1.50 and 1.1.1.51] of rabbit liver were compared. Initial velocity measurements with pyridine-4-aldehyde, 4-benzoylpyridine and androstadione as substrates and inhibition studies with their products indicated that all the enzymes followed an ordered Bi Bi reaction mechanism with coenzyme binding first and leaving last. However, phenylpyruvic acid inhibited 3 alpha-hydroxysteroid dehydrogenase and low-molecular-weight aldehyde reductase noncompetitively with respect to either NADPH or substrate, whereas it inhibited 3 beta-hydroxysteroid dehydrogenase and high-molecular-weight aldehyde reductase uncompetitively. Cibacron blue F3GA dye was a dead-end inhibitor of the enzymes, being competitive with respect to NADPH and noncompetitive with respect to the other substrate, but the Ki value of 3 alpha-hydroxysteroid dehydrogenase for this dye was much higher than those of the other enzymes.

A carbonyl reductase has been extracted into 0.5 M KCl from dog liver and purified to apparent homogeneity by a three-step procedure consisting of chromatography on CM-Sephadex, Matrex green A, and Sephadex G-100 in high-ionic-strength buffers. The enzyme is a dimer composed of two identical subunits of molecular weight 27,000. The pH optimum is 5.5 and the isoelectric point of the enzyme is 9.3. The enzyme reduces aromatic ketones and aldehydes; the aromatic ketones with adjacent medium alkyl chains are the best substrates. Quinones, ketosteroids, prostaglandins, and aliphatic carbonyl compounds are poor or inactive substrates for the enzyme. As a cofactor the enzyme utilizes NADPH, the pro-S hydrogen atom of which is transferred to the substrate. Two moles of NADPH bind to one mole of the enzyme molecule, causing a blue shift and enhancement of the cofactor fluorescence. The reductase reaction is reversible and the equilibrium constant determined at pH 7.0 is 12.8. Steady-state kinetic measurements in both directions suggest that the reaction proceeds through a di-iso ordered bi-bi mechanism.

NADPH-dependent enzymatic reduction of aromatic aldehydes and ketones observed in the cytosol of guinea pig liver was mediated by at least three distinct reductases (AR 1, AR 2, and AR 3), which were separated by DEAE-cellulose chromatography. By several procedures AR 2 and AR 3 were purified to homogeneity, but AR 1 could be purified only 30-fold because of the small amount. These enzymes were found to have similar molecular weights of 34,000 to 36,000 and similar Stokes radii of about 2.5 nm. AR 3 was identical to aldehyde reductase [EC 1.1.1.2] in substrate specificity for aromatic aldehydes and D-glucuronate and specific inhibition by barbiturates. AR 1 and AR 2 acted on aromatic ketones and cyclohexanone as well as aromatic aldehydes at optimal pHs of 5.4 and 6.0, respectively, and were immunochemically distinguished from AR 3. AR 1 was the most sensitive to sulfhydryl reagents, and AR 2 was more stable at 50 degrees C than the other enzymes. Similar heterogeneity was observed in the kidney enzymes, but other tissues had little aldehyde reductase activity and contained only AR 3. In addition, lung contained a high molecular weight aromatic ketone reductase different from the above reductases.

We have kinetically and immunologically demonstrated that testosterone 17 beta-dehydrogenase (NADP+) isoenzymes (EC 1.1.1.64) and aldehyde reductase (EC 1.1.1.2) from guinea-pig liver catalyse the oxidation of benzene dihydrodiol (trans-1,2-dihydroxycyclohexa-3,5-diene) to catechol. One isoenzyme of testosterone 17 beta-dehydrogenase, which has specificity for 5 beta-androstanes, oxidized benzene dihydrodiol at a 3-fold higher rate than 5 beta-dihydrotestosterone, and showed a more than 4-fold higher affinity for benzene dihydrodiol and Vmax. value than did another isoenzyme, which exhibits specificity for 5 alpha-androstanes, and aldehyde reductase. Immunoprecipitation of guinea-pig liver cytosol with antisera against the testosterone 17 beta-dehydrogenase isoenzymes and aldehyde reductase indicated that most of the benzene dihydrodiol dehydrogenase activity in the tissue is due to testosterone 17 beta-dehydrogenase.

Four aldehyde reductases, F1, F2, F3, and F4, were isolated from rabbit liver cytosol to homogeneity by various chromatographic techniques. F2 is an aldehyde reductase with a molecular weight of 32,000, which resembled aldehyde reductases of human liver and pig kidney in properties. It was inhibited in a noncompetitive way by alpha-ketoglutarate and oxaloacetate with Ki values of 4 x 10(-5) M. The other three enzymes were NADPH-dependent aromatic aldehyde-ketone reductases. F1 and F3 were monomeric enzymes with molecular weights of 38,000 and 29,000, respectively. F4 showed a molecular weight of 78,000 on gel filtration, but sodium dodecyl sulfate gel electrophoresis revealed two different subunits with molecular weights of 26,000 and 24,000. The molar ratio of NADPH : F1, F2, or F3 binding was 1 : 1, whereas that of NADPH:F4 binding was 3 : 1. The number of thiol groups in order molecule of F1, F2, F3, and F4, was 4, 4, 4, and 5, respectively. The enzyme activity of F3 was inhibited by addition of an equal mole amount of PCMB. Only F4 was inhibited by metal chelating agents. F1 also catalyzed the interconversion of 3(17)-keto and 3(17) beta-hydroxysteroids, whereas F3 catalyzed oxidoreduction of some 3 alpha-hydroxysteroids of the 5 alpha-series. These results suggest that F1 and F3 are 3(17) beta-hydroxysteroid dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase, respectively. Endogenous substrates for F4 could not be identified in this work. F1 showed the lowest Km value for reduction of aldehydes and ketones among the four reductases. It has been suggested that F1 is the primary enzyme responsible for the reduction of endogeneous aldehydes and xenobiotic aldehydes and ketones in vivo.

A total of 155 patients with hepatocellular carcinoma were studied by celiac and superior mesenteric angiography. Complete (9 patients) or near complete (1 patient) obstruction of the portal vein and formation of hepatopetal collateral veins in the porta hepatis, or the so-called cavernous transformation of the portal vein, were seen in 10 patients. In 4 patients, the first angiogram did not show cavernous transformation, but on the follow-up angiograms cavernous transformation was present. The suggested interval between obstruction of the portal vein and formation of cavernous transformation was no more than 5 wk. The mechanism of cavernous transformation and its clinical implications are briefly discussed.

Two NADPH-dependent aromatic aldehyde-ketone reductases purified from guinea pig liver catalyzed oxidoreduction of 17 beta-hydroxysteroids and 17-ketosteroids. One enzyme efficiently oxidized 5 beta-androstanes and reduced 17-ketosteroids of A/B cis configuration, whereas the other enzyme efficiently oxidized 5 alpha-androstanes and equally reduced both 5 alpha-and 5 beta-androstanes of 17-ketosteroids. However, aromatic aldehydes and ketones, and 3-ketosteroids were irreversibly reduced by the two enzymes. The two enzymes utilized NADP+ or NADPH as cofactor, but little activity with NAD+ or NADH was found. Phosphate ions enhanced the NAD+-dependent dehydrogenase activity and NADH-dependent reductase activity of the two enzymes, whereas the activities with NADP+ and NADPH were not affected. The ratios of the two activities of ketone reduction and 17 beta-hydroxysteroid oxidation of the two enzymes were almost constant during the purification steps after the two enzymes had been separated by DEAE-cellulose chromatography. By kinetic studies and electrophoresis and isoelectric focusing experiments it was confirmed that both of the two enzymes were responsile for the reduction aldehydes, ketones, and ketosteroids and for the oxidation of 17 beta-hydroxysteroids. These results indicate that 17 beta-hydroxysteroid dehydrogenases may play important roles in the metabolism of exogeneous aldehydes and ketones as well as steroids.

Non-histone chromatin proteins prepared from the livers of estrogen-treated and nontreated male chickens were compared by reverse-phase high performance liquid chromatography (RP-HPLC), followed by sodium dodecyl-sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results revealed that the hormone-treated male liver chromatin contained a specific protein corresponding to the vitellogenin-specific protein previously purified from the liver of egg-laying hens (Nakayama 1985). The chicken protein, purified further by gel-filtration high performance liquid chromatography (GF-HPLC), showed specific binding activity to DNA fragments carrying a part of the vitellogenin gene. On the basis of similarities in the elution patterns from GF-HPLC and RP-HPLC as well as in the mobility on SDS-PAGE, we concluded that this hormone-induced protein in the male chicken liver was identical to the vitellogenin-specific protein identified in the hen liver, and assumed it to be a specific regulatory protein for the vitellogenin gene expression. The amino acid composition of this chicken protein has been determined.

19-hydroxyandrostenedione (19-OH A), known for many years as an obligatory intermediate of estrogen biosynthesis, has recently been found to be an amplifier of aldosterone action and in itself a hypertensinogenic steroid (J. Steroid Biochem., 16; 329, 1982). To search the presence of a non-aromatizing andorgen 19-hydroxylase in fetal organs, metabolism of labeled androstenedione(A) in fetal adrenal, liver, lung, brain and kidney was studied. 19-hydroxylase activity was calculated by the amounts of 19-OH A formed from A. The tissue homogenate was incubated with [4-14C]A and NADPH for different periods of time under air. The product, [4-14C] 19-OH A with added carrier standard [6,7-3H] 19-OH A was separated and purified by TLC, acetylation and TLC to constant 3H/14C ratio. The identity of the product was established by C.C.D. and by GC-MS analysis of purified product 19-AcOA in a larger scale adrenal incubation of non-labeled A. 19-hydroxylase activity was 0.9 pmol/min/mg protein for adrenal, but there was a negligible quantity of 19-OH A in lung, brain and kidney. Estrogen production was also assayed by 3H-water method using [1 beta-3H, 4-14C] A (3H/14C = 69.9). No detectable amount of estrogen was found in incubation of any homogenate except for liver. These results indicate that the non-aromatizing 19-hydroxylase activity in fetal adrenal gland is much higher than that in other organs. This is the first report to demonstrate the presence of 19-hydroxylase in human fetal adrenal tissue. It is suggested that 19-OH A secreted from fetal adrenal may also be associated with serum concentration of fetal circulation.

A major and a minor form of dihydrodiol dehydrogenase were co-purified with 17 beta-hydroxysteroid dehydrogenase and aldehyde reductase, respectively, to apparent homogeneity from liver cytosol of male ddY mice. The activities of dihydrodiol dehydrogenase and testosterone dehydrogenase or aldehyde reductase of the two enzyme forms comigrated electrophoretically. The major form of the enzyme oxidized 17 beta-hydroxysteroids and nonsteroidal alicyclic alcohols and reduced 17-ketosteroids and various synthetic carbonyl compounds, showing higher affinity for steroids than for xenobiotics. The activity of this enzyme form toward benzene dihydrodiol and testosterone exhibited identical thermostability and susceptibility to inhibition by quercitrin, SH-reagents, nonsteroidal estrogens and anti-inflammatory agents. On the other hand, the minor form of the enzyme, which oxidized benzene dihydrodiol but not 17 beta-hydroxysteroids, also reduced various aldehydes well and was specifically inhibited by barbiturates and sorbinil. These results indicate that the major form of dihydrodiol dehydrogenase is identical to 17 beta-hydroxysteroid dehydrogenase and the minor enzyme form to aldehyde reductase.

Seven multiforms of indanol dehydrogenase were isolated in a highly purified state from male rabbit liver cytosol. The enzymes were monomeric proteins with similar molecular weights of 30,000-37,000 but with distinct electrophoretic mobilities. All the enzymes oxidized alicyclic alcohols including benzene dihydrodiol and hydroxysteroids at different optimal pH, but showed clear differences in cofactor specificity, steroid specificity, and reversibility of the reaction. Two NADP+-dependent enzymes exhibited both 17 beta-hydroxysteroid dehydrogenase activity for 5 alpha-androstanes and 3 alpha-hydroxysteroid dehydrogenase activity for 5 beta-androstan-3 alpha-ol-17-one. Three of the other enzymes with dual cofactor specificity catalyzed predominantly 5 beta-androstane-3 alpha,17 beta-diol dehydrogenation. The reverse reaction rates of these five enzymes were low, whereas the other two enzymes, which had 3 alpha-hydroxysteroid dehydrogenase activity for 5 alpha-androstanes or 3(17)beta-hydroxysteroid dehydrogenase activity for 5 alpha-androstanes, highly reduced 3-ketosteroids and nonsteroidal aromatic carbonyl compounds with NADPH as a cofactor. All the enzymes exhibited Km values lower for the hydroxysteroids than for the alicyclic alcohols. The results of kinetic analyses with a mixture of 1-indanol and hydroxysteroids, pH and heat stability, and inhibitor sensitivity suggested strongly that, in the seven enzymes, both alicyclic alcohol dehydrogenase and hydroxysteroid dehydrogenase activities reside on a single enzyme protein. On the basis of these data, we suggest that indanol dehydrogenase exists in multiple forms in rabbit liver cytosol and may function in in vivo androgen metabolism.

The methylation state of cellular oncogenes (c-oncs) and epidermal growth factor (EGF) receptor gene from human liver tissues was examined by means of restriction endonuclease analysis. c-myc and EGF receptor gene from hepatocellular carcinoma and fetal liver were substantially hypomethylated in comparison with those genes from normal liver, while the extents of methylation of c-mos and c-Ki-ras genes were the same among these tissues. It can be speculated that the specific hypomethylation of c-myc and EGF receptor genes may be associated with the development of hepatocellular carcinoma.

Kinetic and physicochemical properties of hamster liver diacetyl reductase have been examined. The results of kinetic studies on the reduction of diacetyl and NADPH to acetoin and NADP+ suggest that the reaction follows an Ordered Bi Bi mechanism in which NADPH binds first before diacetyl. The enzyme is a tetrameric glycoprotein of single subunits of a molecular weight of 23,500 with a sedimentation coefficient of 6.0S. The enzyme does not contain Zn, Cu, or Fe. The amino acid composition revealed an unusually low proportion of proline residues (0.9%). p-Chloromercuriphenylsulfonate and phenylglyoxal inactivated the enzyme, but the presence of NADPH prevented the loss of activity due to thiol and arginine modification. The enzyme transferred the pro 4S hydrogen atom of NADPH to the substrate and the binding of the enzyme to NADPH resulted in a red shift of the ultraviolet absorption spectrum of the cofactor.

Antiserum was produced against one of two carbonyl reductases purified from guinea pig liver cytosol to identify the enzymes as testosterone 17 beta-dehydrogenase isozymes. Immunoelectrophoresis and immunoprecipitation with the antiserum indicated that the two reductases had common antigenic sites. The antiserum inhibited most of both carbonyl reductase and testosterone 17 beta-dehydrogenase activities in the purified reductases and in cytosols of liver and kidney.

Two major and two minor forms of dihydrodiol dehydrogenase with similar molecular weights of around 36000 were purified from monkey liver cytosol. All the forms oxidized trans-dihydrodiols of benzene and naphthalene and reduced aromatic aldehydes, but showed differences in charge, specificity for other substrates and inhibitor sensitivity. One major (pI 8.7) and one minor (pI 7.9) form of the enzyme exhibited high activity for alicyclic alcohols and sensitivity to o-phenanthroline. The other major form (pI 6.2) oxidized 3 alpha-hydroxysteroids and was inhibited by dexamethasone and indomethacin, whereas the other minor form (pI 5.8) showed high reductase activity for aldehydes including D-glucuronate and sensitivity to barbital and sorbinil, and cross-reacted with human aldehyde reductase. The results indicate that the multiple forms of monkey liver dihydrodiol dehydrogenase are indanol dehydrogenases, 3 alpha-hydroxysteroid dehydrogenase and aldehyde reductase.